GH-2962: check the whole ctx hierarchy for nullChannel

Fixes #2962

* addressing code style removed comments and addressed review comments

**Cherry-pick to 5.1.x**

Author: michaelwiles

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;
@@ -83,6 +85,7 @@
  * @author Oleg Zhurakousky
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Michael Wiles
  *
  * @see IntegrationContextUtils
  */
@@ -172,18 +175,20 @@ 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);
+					}
+				}
+				if (beanFactory instanceof HierarchicalBeanFactory) {
+					beanFactory = ((HierarchicalBeanFactory) beanFactory).getParentBeanFactory();
 				}
 			}
+			while (nullChannelDefinition == null);
 
 			if (nullChannelDefinition != null &&
 					!NullChannel.class.getName().equals(nullChannelDefinition.getBeanClassName())) {

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

@@ -90,6 +90,7 @@
 import org.springframework.integration.config.GlobalChannelInterceptor;
 import org.springframework.integration.config.IntegrationConverter;
 import org.springframework.integration.config.SpelFunctionFactoryBean;
+import org.springframework.integration.context.IntegrationContextUtils;
 import org.springframework.integration.core.MessageSource;
 import org.springframework.integration.core.MessagingTemplate;
 import org.springframework.integration.endpoint.AbstractEndpoint;
@@ -136,6 +137,7 @@
 /**
  * @author Artem Bilan
  * @author Gary Russell
+ * @author Michael Wiles
  *
  * @since 4.0
  */
@@ -470,6 +472,36 @@ 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() {
+
+		assertThat(this.context.containsBeanDefinition(IntegrationContextUtils.NULL_CHANNEL_BEAN_NAME)).isTrue();
+
+		AnnotationConfigApplicationContext parent;
+		parent = new AnnotationConfigApplicationContext();
+		parent.register(ChildConfiguration.class);
+		parent.setParent(this.context);
+		parent.refresh();
+
+		assertThat(parent.containsBeanDefinition(IntegrationContextUtils.NULL_CHANNEL_BEAN_NAME)).isFalse();
+
+		AnnotationConfigApplicationContext child;
+		child = new AnnotationConfigApplicationContext();
+		child.register(ChildConfiguration.class);
+		child.setParent(parent);
+		child.refresh();
+
+		assertThat(child.containsBeanDefinition(IntegrationContextUtils.NULL_CHANNEL_BEAN_NAME)).isFalse();
+
+		parent.close();
+		child.close();
+	}
+
 	@Test
 	public void testParentChildAnnotationConfiguration() {
 		AnnotationConfigApplicationContext child = new AnnotationConfigApplicationContext();