Raise minimum version to Java 11 (and test on 21 as well)

.github/workflows/ci.yml

@@ -9,15 +9,16 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java: [1.8, 11, 17]
+        java: [11, 17, 21]
     steps:
       - name: Checkout sources
         uses: actions/checkout@v2
 
       - name: Set up JDK
-        uses: actions/setup-java@v1
+        uses: actions/setup-java@v2
         with:
           java-version: ${{ matrix.java }}
+          distribution: 'zulu'
 
       - name: Build
         run: mvn -B package javadoc:javadoc
@@ -29,9 +30,10 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Set up JDK
-        uses: actions/setup-java@v1
+        uses: actions/setup-java@v2
         with:
-          java-version: 1.8
+          java-version: 11
+          distribution: 'zulu'
 
       - name: Build with coverage
         run: mvn -B -Pcoverage clean test jacoco:report-aggregate
@@ -46,9 +48,10 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Set up JDK
-        uses: actions/setup-java@v1
+        uses: actions/setup-java@v2
         with:
-          java-version: 1.8
+          java-version: 11
+          distribution: 'zulu'
 
       - name: Android Lint checks
         run: cd commonmark-android-test && ./gradlew :app:lint

.github/workflows/release.yml

@@ -17,9 +17,10 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Set up Maven Central repository
-        uses: actions/setup-java@v1
+        uses: actions/setup-java@v2
         with:
-          java-version: 1.8
+          java-version: 11
+          distribution: 'zulu'
           server-id: ossrh
           server-username: MAVEN_USERNAME # env variable to use for username in release
           server-password: MAVEN_PASSWORD # env variable to use for password in release

README.md

@@ -23,9 +23,9 @@ full library with a nice API and the following features:
 * Flexible (manipulate the AST after parsing, customize HTML rendering)
 * Extensible (tables, strikethrough, autolinking and more, see below)
 
-The library is supported on Java 8 or later. It should work on Java 7
-and Android too, but that is on a best-effort basis, please report
-problems. For Android the minimum API level is 19, see the
+The library is supported on Java 11 and later. It should work on Android too,
+but that is on a best-effort basis, please report problems. For Android the
+minimum API level is 19, see the
 [commonmark-android-test](commonmark-android-test) directory.
 
 Coordinates for core library (see all on [Maven Central]):

pom.xml

@@ -38,10 +38,9 @@
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
                     <artifactId>maven-compiler-plugin</artifactId>
-                    <version>3.10.1</version>
+                    <version>3.12.1</version>
                     <configuration>
-                        <source>7</source>
-                        <target>7</target>
+                        <release>11</release>
                     </configuration>
                 </plugin>
                 <plugin>