fix for #2962

with tests

Author: Michael Wiles

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

@@ -32,6 +32,8 @@
 
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanClassLoaderAware;
+import org.springframework.beans.factory.BeanFactory;
+import org.springframework.beans.factory.HierarchicalBeanFactory;
 import org.springframework.beans.factory.SmartInitializingSingleton;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.BeanDefinitionHolder;
@@ -172,18 +174,21 @@ private void registerMessagePublishingErrorHandler() {
 	private void registerNullChannel() {
 		if (this.beanFactory.containsBean(IntegrationContextUtils.NULL_CHANNEL_BEAN_NAME)) {
 			BeanDefinition nullChannelDefinition = null;
-			if (this.beanFactory.containsBeanDefinition(IntegrationContextUtils.NULL_CHANNEL_BEAN_NAME)) {
-				nullChannelDefinition =
-						this.beanFactory.getBeanDefinition(IntegrationContextUtils.NULL_CHANNEL_BEAN_NAME);
-			}
-			else {
-				BeanDefinitionRegistry parentBeanFactory =
-						(BeanDefinitionRegistry) this.beanFactory.getParentBeanFactory();
-				if (parentBeanFactory != null) {
-					nullChannelDefinition =
-							parentBeanFactory.getBeanDefinition(IntegrationContextUtils.NULL_CHANNEL_BEAN_NAME);
+			BeanFactory beanFactory = this.beanFactory;
+			do {
+				if (beanFactory instanceof ConfigurableListableBeanFactory) {
+					ConfigurableListableBeanFactory listable = (ConfigurableListableBeanFactory) beanFactory;
+					if (listable.containsBeanDefinition(IntegrationContextUtils.NULL_CHANNEL_BEAN_NAME)) {
+						nullChannelDefinition = listable
+								.getBeanDefinition(IntegrationContextUtils.NULL_CHANNEL_BEAN_NAME);
+					}
 				}
-			}
+				// don't think it will hurt to always find the parent
+				if (beanFactory instanceof HierarchicalBeanFactory) {
+					beanFactory = ((HierarchicalBeanFactory) beanFactory).getParentBeanFactory();
+				}
+				// will definitely be found as containsBean returned true - but also want to be defensive in case of NPE
+			} while (nullChannelDefinition == null && beanFactory != null); // not sure if beanFactroy not null is necessary
 
 			if (nullChannelDefinition != null &&
 					!NullChannel.class.getName().equals(nullChannelDefinition.getBeanClassName())) {

spring-integration-core/src/test/java/org/springframework/integration/configuration/EnableIntegrationTests.java

@@ -470,6 +470,30 @@ public void testMessagingGateway() throws InterruptedException {
 		assertThat(this.asyncAnnotationProcessThread.get()).isNotSameAs(Thread.currentThread());
 	}
 
+	/**
+	 * Just creates an interim context to confirm that the DefaultConfiguringBeanFactoryPostProcessor 
+	 * does not fail when there is an extra application context in the hierarchy.
+	 */
+	@Test
+	public void testDoubleParentChildAnnotationConfiguration() {
+		AnnotationConfigApplicationContext parent;
+		{
+			parent = new AnnotationConfigApplicationContext();
+			parent.register(ChildConfiguration.class);
+			parent.setParent(this.context);
+			parent.refresh();
+		}
+		AnnotationConfigApplicationContext child;
+		{
+			child = new AnnotationConfigApplicationContext();
+			child.register(ChildConfiguration.class);
+			child.setParent(parent);
+			child.refresh();
+		}
+		parent.close();
+		child.close();
+	}
+	
 	@Test
 	public void testParentChildAnnotationConfiguration() {
 		AnnotationConfigApplicationContext child = new AnnotationConfigApplicationContext();