INT-3884: Outbound Gateway replyChannel in Chain

JIRA: https://jira.spring.io/browse/INT-3884

Previously, an outbound gateway within a chain allowed a `reply-channel` attribute
but it was ignored. The gateway's output channel is set to send the message to
the next element in the chain, or the chain's output channel if the gateway is
the last element.

Tighten the parser logic to detect and disallow a reply channel within a chain.

Polishing

spring-integration-core/src/main/java/org/springframework/integration/config/xml/AbstractConsumerEndpointParser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2015 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.
@@ -95,12 +95,19 @@ public abstract class AbstractConsumerEndpointParser extends AbstractBeanDefinit
 		String inputChannelAttributeName = this.getInputChannelAttributeName();
 		boolean hasInputChannelAttribute = element.hasAttribute(inputChannelAttributeName);
 		if (parserContext.isNested()) {
+			String elementDescription = IntegrationNamespaceUtils.createElementDescription(element);
 			if (hasInputChannelAttribute) {
-				String elementDescription = IntegrationNamespaceUtils.createElementDescription(element);
 				parserContext.getReaderContext().error("The '" + inputChannelAttributeName
 						+ "' attribute isn't allowed for a nested (e.g. inside a <chain/>) endpoint element: "
 						+ elementDescription + ".", element);
 			}
+			if (!replyChannelInChainAllowed(element)) {
+				if (StringUtils.hasText(element.getAttribute("reply-channel"))) {
+					parserContext.getReaderContext().error("The 'reply-channel' attribute isn't"
+							+ " allowed for a nested (e.g. inside a <chain/>) outbound gateway element: "
+							+ elementDescription + ".", element);
+				}
+			}
 			return handlerBeanDefinition;
 		}
 		else {
@@ -168,4 +175,14 @@ public abstract class AbstractConsumerEndpointParser extends AbstractBeanDefinit
 		return null;
 	}
 
+	/**
+	 * Override to allow 'reply-channel' within a chain, for components where it
+	 * makes sense (e.g. enricher). Default is false for outbound gateways, else true.
+	 * @return true to allow a reply channel attribute within a chain.
+	 */
+	protected boolean replyChannelInChainAllowed(Element element) {
+		String localName = element.getLocalName();
+		return localName == null || !localName.contains("outbound-gateway");
+	}
+
 }

spring-integration-core/src/main/java/org/springframework/integration/config/xml/EnricherParser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2015 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.
@@ -42,6 +42,7 @@ import org.springframework.util.xml.DomUtils;
  * @author Artem Bilan
  * @author Liujiong
  * @author Kris Jacyna
+ * @author Gary Russell
  * @since 2.1
  */
 public class EnricherParser extends AbstractConsumerEndpointParser {
@@ -201,4 +202,9 @@ public class EnricherParser extends AbstractConsumerEndpointParser {
 		return builder;
 	}
 
+	@Override
+	protected boolean replyChannelInChainAllowed(Element element) {
+		return true;
+	}
+
 }

spring-integration-core/src/test/java/org/springframework/integration/config/xml/EnricherParserTests5-context.xml

@@ -11,16 +11,20 @@
 
 	<channel id="requestChannel"/>
 
+	<channel id="replyChannel"/>
+
 	<channel id="errChannel"/>
 
 	<channel id="outputChannel">
 		<queue />
 	</channel>
 
-	<enricher id="enricher" 
-			input-channel="inputChannel" request-channel="requestChannel" 
-			output-channel="outputChannel" error-channel="errChannel">
-		<property name="name" expression="'Mr. ' + payload.name"/>
-	</enricher>
-
+	<chain input-channel="inputChannel" output-channel="outputChannel">
+		<enricher id="enricher"
+				  request-channel="requestChannel"
+				  reply-channel="replyChannel"
+				  error-channel="errChannel">
+			<property name="name" expression="'Mr. ' + payload.name"/>
+		</enricher>
+	</chain>
 </beans:beans>