GH-9931: Make consumer endpoints dependant on ChannelInitializer

Fixes: #9931
Issue link: #9931

If no message channel bean is declared explicitly, the XML parser for endpoints
register such a candidate into the global `ChannelInitializer`.
This way, the channel is created when this bean is initialized.
However, there are cases when endpoint bean could be called before `ChannelInitializer` initialization.

* Add `consumerEndpointBuilder.addDependsOn(IntegrationContextUtils.AUTO_CREATE_CHANNEL_CANDIDATES_BEAN_NAME);`
into the `AbstractConsumerEndpointParser` to ensure that `ChannelInitializer` bean is initialized
before the called endpoint bean.
* Adjust `ChannelInitializer` logic to use `registerSingleton()` API instead of `registerBeanDefinition()`
since the last one may cause problems with beans cache when this API is called at runtime.

**Auto-cherry-pick to `6.4.x`**

Author: artembilan

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -25,17 +25,18 @@
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanFactoryAware;
 import org.springframework.beans.factory.InitializingBean;
-import org.springframework.beans.factory.support.BeanDefinitionRegistry;
+import org.springframework.beans.factory.support.DefaultListableBeanFactory;
+import org.springframework.integration.channel.DirectChannel;
 import org.springframework.integration.context.IntegrationContextUtils;
 import org.springframework.util.Assert;
 
 /**
- * A {@link InitializingBean} implementation that is responsible for creating
+ * An {@link InitializingBean} implementation that is responsible for creating
  * channels that are not explicitly defined but identified via the 'input-channel'
  * attribute of the corresponding endpoints.
- *
+ * <p>
  * This bean plays a role of pre-instantiator since it is instantiated and
- * initialized as the very first bean of all SI beans using
+ * initialized as the very first bean of all Spring Integration beans using
  * {@link org.springframework.integration.config.xml.AbstractIntegrationNamespaceHandler}.
  *
  * @author Oleg Zhurakousky
@@ -48,7 +49,7 @@ public final class ChannelInitializer implements BeanFactoryAware, InitializingB
 
 	private static final Log LOGGER = LogFactory.getLog(ChannelInitializer.class);
 
-	private volatile BeanFactory beanFactory;
+	private volatile DefaultListableBeanFactory beanFactory;
 
 	private volatile boolean autoCreate = true;
 
@@ -61,49 +62,38 @@ public void setAutoCreate(boolean autoCreate) {
 
 	@Override
 	public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
-		this.beanFactory = beanFactory;
+		this.beanFactory = (DefaultListableBeanFactory) beanFactory;
 	}
 
 	@Override
 	public void afterPropertiesSet() {
 		Assert.notNull(this.beanFactory, "'beanFactory' must not be null");
-		if (!this.autoCreate) {
-			return;
-		}
-		else {
+		if (this.autoCreate) {
 			AutoCreateCandidatesCollector channelCandidatesCollector =
 					this.beanFactory.getBean(IntegrationContextUtils.AUTO_CREATE_CHANNEL_CANDIDATES_BEAN_NAME,
 							AutoCreateCandidatesCollector.class);
 			// at this point channelNames are all resolved with placeholders and SpEL
-			Collection<String> channelNames = channelCandidatesCollector.getChannelNames();
+			Collection<String> channelNames = channelCandidatesCollector.channelNames;
 			if (channelNames != null) {
 				for (String channelName : channelNames) {
 					if (!this.beanFactory.containsBean(channelName)) {
 						if (LOGGER.isDebugEnabled()) {
 							LOGGER.debug("Auto-creating channel '" + channelName + "' as DirectChannel");
 						}
-						IntegrationConfigUtils.autoCreateDirectChannel(channelName,
-								(BeanDefinitionRegistry) this.beanFactory);
+						DirectChannel channelToRegister = new DirectChannel();
+						this.beanFactory.registerSingleton(channelName, channelToRegister);
+						this.beanFactory.initializeBean(channelToRegister, channelName);
 					}
 				}
 			}
 		}
 	}
 
-	/*
-	 * Collects candidate channel names to be auto-created by ChannelInitializer
+	/**
+	 * Collects candidate channel names to be auto-created by {@link ChannelInitializer}.
+	 * @param channelNames the auto-create candidate channel bean names.
 	 */
-	public static class AutoCreateCandidatesCollector {
-
-		private final Collection<String> channelNames;
-
-		AutoCreateCandidatesCollector(Collection<String> channelNames) {
-			this.channelNames = channelNames;
-		}
-
-		public Collection<String> getChannelNames() {
-			return this.channelNames;
-		}
+	public record AutoCreateCandidatesCollector(Collection<String> channelNames) {
 
 	}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -29,6 +29,7 @@
 import org.springframework.beans.factory.support.AbstractBeanDefinition;
 import org.springframework.beans.factory.support.BeanDefinitionBuilder;
 import org.springframework.beans.factory.support.BeanDefinitionReaderUtils;
+import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.support.ManagedList;
 import org.springframework.beans.factory.support.ManagedSet;
 import org.springframework.beans.factory.xml.AbstractBeanDefinitionParser;
@@ -148,7 +149,7 @@ protected final AbstractBeanDefinition parseInternal(Element element, ParserCont
 		String inputChannelName = element.getAttribute(inputChannelAttributeName);
 
 		if (!parserContext.getRegistry().containsBeanDefinition(inputChannelName)) {
-			registerChannelForCreation(parserContext, inputChannelName);
+			registerChannelForCreation(parserContext, inputChannelName, builder);
 		}
 		IntegrationNamespaceUtils.checkAndConfigureFixedSubscriberChannel(element, parserContext, inputChannelName,
 				handlerBeanName);
@@ -177,12 +178,17 @@ private void poller(Element element, ParserContext parserContext, BeanDefinition
 		}
 	}
 
-	private void registerChannelForCreation(ParserContext parserContext, String inputChannelName) {
-		if (parserContext.getRegistry()
-				.containsBeanDefinition(IntegrationContextUtils.AUTO_CREATE_CHANNEL_CANDIDATES_BEAN_NAME)) {
+	private void registerChannelForCreation(ParserContext parserContext, String inputChannelName,
+			BeanDefinitionBuilder consumerEndpointBuilder) {
 
-			BeanDefinition channelRegistry = parserContext.getRegistry().
-					getBeanDefinition(IntegrationContextUtils.AUTO_CREATE_CHANNEL_CANDIDATES_BEAN_NAME);
+		BeanDefinitionRegistry beanDefinitionRegistry = parserContext.getRegistry();
+
+		if (beanDefinitionRegistry.containsBeanDefinition(
+				IntegrationContextUtils.AUTO_CREATE_CHANNEL_CANDIDATES_BEAN_NAME)) {
+
+			BeanDefinition channelRegistry =
+					beanDefinitionRegistry.getBeanDefinition(
+							IntegrationContextUtils.AUTO_CREATE_CHANNEL_CANDIDATES_BEAN_NAME);
 			ConstructorArgumentValues caValues = channelRegistry.getConstructorArgumentValues();
 			ValueHolder vh = caValues.getArgumentValue(0, Collection.class);
 			if (vh == null) { //although it should never happen if it does we can fix it
@@ -194,11 +200,13 @@ private void registerChannelForCreation(ParserContext parserContext, String inpu
 					(Collection<String>) caValues.getArgumentValue(0, Collection.class)
 							.getValue(); // NOSONAR see comment above
 			channelCandidateNames.add(inputChannelName); // NOSONAR
+
+			consumerEndpointBuilder.addDependsOn(IntegrationContextUtils.AUTO_CREATE_CHANNEL_CANDIDATES_BEAN_NAME);
 		}
 		else {
 			parserContext.getReaderContext().error("Failed to locate '" +
 							IntegrationContextUtils.AUTO_CREATE_CHANNEL_CANDIDATES_BEAN_NAME + "'",
-					parserContext.getRegistry());
+					beanDefinitionRegistry);
 		}
 	}