GH-2600: Fix Kotlin Listener List<Message<*>>

Resolves #2600

Also reproduced in Java with

	@KafkaListener(id = "kgh2600", topics = "kgh2600", batch = "true")
	void listen(List<? extends Message<?>> in) {
		System.out.println(in);
	}

MMLA did not handle a `WildcardType` as the list element type.

Also tested with reporter's Kotlin reproducer.

**cherry-pick to 2.9.x** (pattern matching instanceof will need to be changed)

Author: garyrussell

spring-kafka/src/main/java/org/springframework/kafka/listener/adapter/MessagingMessageListenerAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2022 the original author or authors.
+ * Copyright 2016-2023 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -683,11 +683,10 @@ else if (parameterizedType.getRawType().equals(List.class)
 				this.isConsumerRecordList = paramType.equals(ConsumerRecord.class)
 						|| (isSimpleListOfConsumerRecord(paramType)
 						|| isListOfConsumerRecordUpperBounded(paramType));
-				boolean messageHasGeneric = paramType instanceof ParameterizedType pType
-						&& pType.getRawType().equals(Message.class);
-				this.isMessageList = paramType.equals(Message.class) || messageHasGeneric;
-				if (messageHasGeneric) {
-					genericParameterType = ((ParameterizedType) paramType).getActualTypeArguments()[0];
+				boolean messageWithGeneric = isMessageWithGeneric(paramType);
+				this.isMessageList = paramType.equals(Message.class) || messageWithGeneric;
+				if (messageWithGeneric) {
+					genericParameterType = messagePayloadType(paramType);
 				}
 			}
 			else {
@@ -697,6 +696,24 @@ else if (parameterizedType.getRawType().equals(List.class)
 		return genericParameterType;
 	}
 
+	private Type messagePayloadType(Type paramType) {
+		if (paramType instanceof ParameterizedType pType) {
+			return pType.getActualTypeArguments()[0];
+		}
+		else {
+			return ((ParameterizedType) ((WildcardType) paramType).getUpperBounds()[0]).getActualTypeArguments()[0];
+		}
+	}
+
+	private boolean isMessageWithGeneric(Type paramType) {
+		boolean messageHasGeneric = (paramType instanceof ParameterizedType pType
+				&& pType.getRawType().equals(Message.class))
+				|| (isWildCardWithUpperBound(paramType)
+						&& ((WildcardType) paramType).getUpperBounds()[0] instanceof ParameterizedType wildCardZero
+						&& wildCardZero.getRawType().equals(Message.class));
+		return messageHasGeneric;
+	}
+
 	private boolean isSimpleListOfConsumerRecord(Type paramType) {
 		return paramType instanceof ParameterizedType pType && pType.getRawType().equals(ConsumerRecord.class);
 	}

spring-kafka/src/test/java/org/springframework/kafka/annotation/EnableKafkaIntegrationTests.java

@@ -651,6 +651,11 @@ public void testBatchMessages() throws Exception {
 		assertThat(list.get(0)).isInstanceOf(Message.class);
 		Message<?> m = (Message<?>) list.get(0);
 		assertThat(m.getPayload()).isInstanceOf(String.class);
+		assertThat(this.listener.latch14a.await(10, TimeUnit.SECONDS)).isTrue();
+		assertThat(this.listener.payload2).isInstanceOf(List.class);
+		list = (List<?>) this.listener.payload2;
+		assertThat(list.size()).isGreaterThan(0);
+		assertThat(list.get(0)).isInstanceOf(Message.class);
 	}
 
 	@Test
@@ -1807,6 +1812,8 @@ static class Listener implements ConsumerSeekAware {
 
 		final CountDownLatch latch14 = new CountDownLatch(1);
 
+		final CountDownLatch latch14a = new CountDownLatch(1);
+
 		final CountDownLatch latch15 = new CountDownLatch(1);
 
 		final CountDownLatch latch16 = new CountDownLatch(1);
@@ -1845,6 +1852,8 @@ static class Listener implements ConsumerSeekAware {
 
 		volatile Object payload;
 
+		volatile Object payload2;
+
 		volatile Exception validationException;
 
 		volatile String convertedKey;
@@ -2083,6 +2092,12 @@ public void listen14(List<Message<?>> list) {
 			this.latch14.countDown();
 		}
 
+		@KafkaListener(id = "list5a", topics = "annotated18", containerFactory = "batchFactory")
+		public void listen14a(List<? extends Message<?>> list) {
+			this.payload2 = list;
+			this.latch14a.countDown();
+		}
+
 		@KafkaListener(id = "list6", topics = "annotated19", containerFactory = "batchManualFactory2")
 		public void listen15(List<Message<?>> list, Acknowledgment ack) {
 			this.payload = list;