INT-1107 POJO Aggregator can return a Message without that being wrapped in another Message.

org.springframework.integration/src/main/java/org/springframework/integration/aggregator/AbstractAggregatingMessageGroupProcessor.java

@@ -40,13 +40,17 @@ public abstract class AbstractAggregatingMessageGroupProcessor implements Messag
 
 	private final Log logger = LogFactory.getLog(this.getClass());
 
+	@SuppressWarnings("unchecked")
 	public final void processAndSend(MessageGroup group, MessageChannelTemplate channelTemplate,
 			MessageChannel outputChannel) {
 		Assert.notNull(group, "MessageGroup must not be null");
 		Assert.notNull(outputChannel, "'outputChannel' must not be null");
 		Object payload = this.aggregatePayloads(group);
 		Map<String, Object> headers = this.aggregateHeaders(group);
-		Message<?> message = MessageBuilder.withPayload(payload).copyHeadersIfAbsent(headers).build();
+		MessageBuilder<?> builder = (payload instanceof Message)
+				? MessageBuilder.fromMessage((Message<?>) payload)
+				: MessageBuilder.withPayload(payload);
+		Message<?> message = builder.copyHeadersIfAbsent(headers).build();
 		channelTemplate.send(message, outputChannel);
 	}
 

org.springframework.integration/src/test/java/org/springframework/integration/aggregator/integration/MethodInvokingAggregatorReturningMessageTests-context.xml

@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<beans:beans xmlns:beans="http://www.springframework.org/schema/beans"
+	xmlns="http://www.springframework.org/schema/integration"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://www.springframework.org/schema/beans
+			http://www.springframework.org/schema/beans/spring-beans.xsd
+			http://www.springframework.org/schema/integration
+			http://www.springframework.org/schema/integration/spring-integration.xsd">
+
+	<channel id="pojoOutput">
+		<queue/>
+	</channel>
+
+	<channel id="defaultOutput">
+		<queue/>
+	</channel>
+
+	<splitter input-channel="pojoInput" output-channel="pojoAggregator"/>
+
+	<aggregator input-channel="pojoAggregator" output-channel="pojoOutput" method="aggregate">
+		<beans:bean class="org.springframework.integration.aggregator.integration.MethodInvokingAggregatorReturningMessageTests$TestAggregator"/>
+	</aggregator>
+
+	<splitter input-channel="defaultInput" output-channel="defaultAggregator"/>
+
+	<aggregator input-channel="defaultAggregator" output-channel="defaultOutput"/>
+
+</beans:beans>

org.springframework.integration/src/test/java/org/springframework/integration/aggregator/integration/MethodInvokingAggregatorReturningMessageTests.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2002-2010 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.
+ * 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 org.springframework.integration.aggregator.integration;
+
+import static org.junit.Assert.assertFalse;
+
+import java.util.Collections;
+import java.util.List;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.integration.channel.DirectChannel;
+import org.springframework.integration.channel.PollableChannel;
+import org.springframework.integration.core.Message;
+import org.springframework.integration.message.MessageBuilder;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+/**
+ * @author Mark Fisher
+ */
+@ContextConfiguration
+@RunWith(SpringJUnit4ClassRunner.class)
+public class MethodInvokingAggregatorReturningMessageTests {
+
+	@Autowired
+	DirectChannel pojoInput;
+
+	@Autowired
+	DirectChannel defaultInput;
+
+	@Autowired
+	PollableChannel pojoOutput;
+
+	@Autowired
+	PollableChannel defaultOutput;
+
+
+	@Test // INT-1107
+	public void messageReturningPojoAggregatorResultIsNotWrappedInAnotherMessage() {
+		List<String> payload = Collections.singletonList("test");
+		pojoInput.send(MessageBuilder.withPayload(payload).build());
+		Message<?> result = pojoOutput.receive();
+		assertFalse(Message.class.isAssignableFrom(result.getPayload().getClass()));
+	}
+
+	@Test
+	public void defaultAggregatorResultIsNotWrappedInAnotherMessage() {
+		List<String> payload = Collections.singletonList("test");
+		defaultInput.send(MessageBuilder.withPayload(payload).build());
+		Message<?> result = defaultOutput.receive();
+		assertFalse(Message.class.isAssignableFrom(result.getPayload().getClass()));
+	}
+
+
+	@SuppressWarnings("unused")
+	private static class TestAggregator {
+
+		public Message<?> aggregate(final List<Message<?>> messages) {
+			List<String> payload = Collections.singletonList("foo");
+			return MessageBuilder.withPayload(payload).setHeader("bar", 123).build();
+		}
+	}
+
+}