GH-1189: @SendTo for @KafkaHandler after error is handled

Sending the result from a `KafkaListenerErrorHandler` was broken
for `@KafkaHandler` because the send to expression
was lost.

Author: Zhiyang.Wang1

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2023 the original author or authors.
+ * Copyright 2016-2024 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.
@@ -337,6 +337,17 @@ private boolean assignPayload(MethodParameter methodParameter, Class<?> payloadC
 				&& methodParameter.getParameterType().isAssignableFrom(payloadClass);
 	}
 
+	@Nullable
+	public InvocationResult getInvocationResultFor(Object result, Object inboundPayload) {
+
+		InvocableHandlerMethod handler = findHandlerForPayload(inboundPayload.getClass());
+		if (handler != null) {
+			return new InvocationResult(result, this.handlerSendTo.get(handler),
+					this.handlerReturnsMessage.get(handler));
+		}
+		return null;
+	}
+
 	private static final class PayloadValidator extends PayloadMethodArgumentResolver {
 
 		PayloadValidator(Validator validator) {

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2015-2021 the original author or authors.
+ * Copyright 2015-2024 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.
@@ -16,6 +16,7 @@
 
 package org.springframework.kafka.listener.adapter;
 
+import org.springframework.lang.Nullable;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.handler.invocation.InvocableHandlerMethod;
 
@@ -98,4 +99,13 @@ public Object getBean() {
 		}
 	}
 
+	@Nullable
+	public InvocationResult getInvocationResultFor(Object result, @Nullable Object inboundPayload) {
+
+		if (this.delegatingHandler != null && inboundPayload != null) {
+			return this.delegatingHandler.getInvocationResultFor(result, inboundPayload);
+		}
+		return null;
+	}
+
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2023 the original author or authors.
+ * Copyright 2016-2024 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.
@@ -26,6 +26,7 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.concurrent.CompletableFuture;
 import java.util.stream.Collectors;
 
@@ -462,16 +463,14 @@ protected void handleResult(Object resultArg, Object request, @Nullable Acknowle
 		String replyTopic = evaluateReplyTopic(request, source, resultArg);
 		Assert.state(replyTopic == null || this.replyTemplate != null,
 				"a KafkaTemplate is required to support replies");
-		Object result;
-		boolean messageReturnType;
-		if (resultArg instanceof InvocationResult invocationResult) {
-			result = invocationResult.getResult();
-			messageReturnType = invocationResult.isMessageReturnType();
-		}
-		else {
-			result = resultArg;
-			messageReturnType = this.messageReturnType;
-		}
+
+		Object result = resultArg instanceof InvocationResult invocationResult ?
+				invocationResult.getResult() :
+				resultArg;
+		boolean messageReturnType = resultArg instanceof InvocationResult invocationResult ?
+				invocationResult.isMessageReturnType() :
+				this.messageReturnType;
+
 		if (result instanceof CompletableFuture<?> completable) {
 			if (acknowledgment == null || !acknowledgment.isOutOfOrderCommit()) {
 				this.logger.warn("Container 'Acknowledgment' must be async ack for Future<?> return type; "
@@ -677,9 +676,11 @@ protected void handleException(Object records, @Nullable Acknowledgment acknowle
 				if (NULL_MESSAGE.equals(message)) {
 					message = new GenericMessage<>(records);
 				}
-				Object result = this.errorHandler.handleError(message, e, consumer, acknowledgment);
-				if (result != null) {
-					handleResult(result, records, acknowledgment, consumer, message);
+				Object errorResult = this.errorHandler.handleError(message, e, consumer, acknowledgment);
+				if (errorResult != null && !(errorResult instanceof InvocationResult)) {
+					Object result = this.handlerMethod.getInvocationResultFor(errorResult, message.getPayload());
+					handleResult(Objects.requireNonNullElse(result, errorResult),
+							records, acknowledgment, consumer, message);
 				}
 			}
 			catch (Exception ex) {

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

@@ -470,10 +470,12 @@ public void testMulti() throws Exception {
 		assertThat(this.multiListener.latch2.await(60, TimeUnit.SECONDS)).isTrue();
 		ConsumerRecord<Integer, String> reply = KafkaTestUtils.getSingleRecord(consumer, "annotated8reply");
 		assertThat(reply.value()).isEqualTo("OK");
-		consumer.close();
 
 		template.send("annotated8", 0, 1, "junk");
 		assertThat(this.multiListener.errorLatch.await(60, TimeUnit.SECONDS)).isTrue();
+		ConsumerRecord<Integer, String> reply2 = KafkaTestUtils.getSingleRecord(consumer, "annotated8reply");
+		consumer.close();
+		assertThat(reply2.value()).isEqualTo("JUNK intentional");
 		assertThat(this.multiListener.meta).isNotNull();
 	}
 
@@ -1754,7 +1756,8 @@ public Object resolveArgument(MethodParameter parameter, Message<?> message) {
 		public KafkaListenerErrorHandler consumeMultiMethodException(MultiListenerBean listener) {
 			return (m, e) -> {
 				listener.errorLatch.countDown();
-				return null;
+				String payload = m.getPayload().toString().toUpperCase();
+				return payload + " " + e.getCause().getMessage();
 			};
 		}
 
@@ -2468,6 +2471,7 @@ static class MultiListenerBean {
 		volatile ConsumerRecordMetadata meta;
 
 		@KafkaHandler
+		@SendTo("annotated8reply")
 		public void bar(@NonNull String bar, @Header(KafkaHeaders.RECORD_METADATA) ConsumerRecordMetadata meta) {
 			if ("junk".equals(bar)) {
 				throw new RuntimeException("intentional");

spring-kafka/src/test/kotlin/org/springframework/kafka/listener/EnableKafkaKotlinCoroutinesTests.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2016-2023 the original author or authors.
+ * Copyright 2016-2024 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.
@@ -56,7 +56,7 @@ import java.util.concurrent.TimeUnit
 @SpringJUnitConfig
 @DirtiesContext
 @EmbeddedKafka(topics = ["kotlinAsyncTestTopic1", "kotlinAsyncTestTopic2",
-		"kotlinAsyncBatchTestTopic1", "kotlinAsyncBatchTestTopic2"])
+		"kotlinAsyncBatchTestTopic1", "kotlinAsyncBatchTestTopic2", "sendTopicReply1"])
 class EnableKafkaKotlinCoroutinesTests {
 
 	@Autowired
@@ -96,7 +96,7 @@ class EnableKafkaKotlinCoroutinesTests {
 	@Test
 	fun `test checkedKh reply`() {
 		this.template.send("kotlinAsyncTestTopic3", "foo")
-		val cr = this.template.receive("sendTopic1", 0, 0, Duration.ofSeconds(30))
+		val cr = this.template.receive("sendTopicReply1", 0, 0, Duration.ofSeconds(30))
 		assertThat(cr.value()).isEqualTo("FOO")
 	}
 
@@ -105,7 +105,7 @@ class EnableKafkaKotlinCoroutinesTests {
 	class Listener {
 
 		@KafkaHandler
-		@SendTo("sendTopic1")
+		@SendTo("sendTopicReply1")
 		suspend fun handler1(value: String) : String {
 			return value.uppercase()
 		}