reproduce exception with PriorityQueue with lambda expression

build.sbt

@@ -31,8 +31,8 @@ val sharedSettings = mimaDefaultSettings ++ Seq(
   scalariformPreferences := formattingPreferences,
   scalariformAutoformat := false,
   // Twitter Hadoop needs this, sorry 1.7 fans
-  javacOptions ++= Seq("-target", "1.6", "-source", "1.6", "-Xlint:-options"),
-  javacOptions in doc := Seq("-source", "1.6"),
+  javacOptions ++= Seq("-target", "1.8", "-source", "1.8", "-Xlint:-options"),
+  javacOptions in doc := Seq("-source", "1.8"),
   resolvers ++= Seq(
     Opts.resolver.sonatypeSnapshots,
     Opts.resolver.sonatypeReleases

chill-java/src/test/java/com/twitter/chill/java/TestPriorityQueue.java

@@ -0,0 +1,55 @@
+package com.twitter.chill.java;
+
+import com.esotericsoftware.kryo.Kryo;
+import com.esotericsoftware.kryo.io.Input;
+import com.esotericsoftware.kryo.io.Output;
+
+import java.util.Comparator;
+import java.util.PriorityQueue;
+
+public class TestPriorityQueue {
+
+	private static final Kryo kryo = new Kryo();
+
+	private static final PriorityQueue<String> test_priority_queue1 =
+			new PriorityQueue<>((o1, o2) -> o1.length() - o2.length() - 1);
+
+	private static final PriorityQueue<String> test_priority_queue2 =
+			new PriorityQueue<>(new Comparator<String>() {
+				@Override
+				public int compare(String o1, String o2) {
+					return o1.length() - o2.length() - 1;
+				}
+			});
+
+	static {
+		test_priority_queue1.add("12345");
+		test_priority_queue1.add("123");
+		test_priority_queue1.add("12456789");
+
+		test_priority_queue2.add("12345");
+		test_priority_queue2.add("123");
+		test_priority_queue2.add("12456789");
+	}
+
+	public static PriorityQueue<String> serializeAndDeserializeQueue1() {
+		Output output = new Output(1000, -1);
+		kryo.writeClassAndObject(output, test_priority_queue1);
+		Input input = new Input(output.toBytes());
+		return (PriorityQueue<String>) kryo.readClassAndObject(input);
+	}
+
+	public static PriorityQueue<String> serializeAndDeserializeQueue1(Kryo kryo) {
+		Output output = new Output(1000, -1);
+		kryo.writeClassAndObject(output, test_priority_queue1);
+		Input input = new Input(output.toBytes());
+		return (PriorityQueue<String>) kryo.readClassAndObject(input);
+	}
+
+	public static PriorityQueue<String> serializeAndDeserializeQueue2(Kryo kryo) {
+		Output output = new Output(1000, -1);
+		kryo.writeClassAndObject(output, test_priority_queue2);
+		Input input = new Input(output.toBytes());
+		return (PriorityQueue<String>) kryo.readClassAndObject(input);
+	}
+}

chill-java/src/test/scala/com/twitter/chill/java/PriorityQueueTest.scala

@@ -16,12 +16,8 @@ limitations under the License.
 
 package com.twitter.chill.java
 
-import org.scalatest._
-
 import com.esotericsoftware.kryo.Kryo
-import com.esotericsoftware.kryo.io.Input
-import com.esotericsoftware.kryo.io.Output
-
+import com.esotericsoftware.kryo.io.{Input, Output}
 import org.objenesis.strategy.StdInstantiatorStrategy
 import org.scalatest.matchers.should.Matchers
 import org.scalatest.wordspec.AnyWordSpec
@@ -34,6 +30,24 @@ class PriorityQueueSpec extends AnyWordSpec with Matchers {
     k.readClassAndObject(in).asInstanceOf[A]
   }
 
+  "A PriorityQueue Serializer" should {
+    "serialize PriorityQueue with lambda expression" in {
+
+      val kryo = new Kryo()
+      kryo.setInstantiatorStrategy(new StdInstantiatorStrategy)
+      PriorityQueueSerializer.registrar()(kryo)
+
+      // this works well without registered PriorityQueueSerializer
+      TestPriorityQueue.serializeAndDeserializeQueue1()
+
+      // this works well with registered PriorityQueueSerializer and PriorityQueue instance (with non-lambda expression)
+      TestPriorityQueue.serializeAndDeserializeQueue2(kryo)
+
+      // this should work well but failed with PriorityQueueSerializer registered in kryo and PriorityQueue instance (with lambda expression)
+      TestPriorityQueue.serializeAndDeserializeQueue1(kryo)
+    }
+  }
+
   "A PriorityQueue Serializer" should {
     "handle PriorityQueue" in {
       import scala.collection.JavaConverters._