Declare empty default postProcessBeanFactory method

Closes gh-31476

spring-beans/src/main/java/org/springframework/beans/factory/support/BeanDefinitionRegistryPostProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2010 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -18,6 +18,7 @@ package org.springframework.beans.factory.support;
 
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
+import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 
 /**
  * Extension to the standard {@link BeanFactoryPostProcessor} SPI, allowing for
@@ -42,4 +43,14 @@ public interface BeanDefinitionRegistryPostProcessor extends BeanFactoryPostProc
 	 */
 	void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException;
 
+	/**
+	 * Empty implementation of {@link BeanFactoryPostProcessor#postProcessBeanFactory}
+	 * since custom {@code BeanDefinitionRegistryPostProcessor} implementations will
+	 * typically only provide a {@link #postProcessBeanDefinitionRegistry} method.
+	 * @since 6.1
+	 */
+	@Override
+	default void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
+	}
+
 }

spring-context/src/test/java/org/springframework/context/support/BeanFactoryPostProcessorTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -193,10 +193,6 @@ class BeanFactoryPostProcessorTests {
 		public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
 			registry.registerBeanDefinition("bfpp1", new RootBeanDefinition(TestBeanFactoryPostProcessor.class));
 		}
-
-		@Override
-		public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
-		}
 	}
 
 
@@ -224,10 +220,6 @@ class BeanFactoryPostProcessorTests {
 			registry.registerBeanDefinition("anotherpp", new RootBeanDefinition(TestBeanDefinitionRegistryPostProcessor.class));
 			registry.registerBeanDefinition("ppp", new RootBeanDefinition(PrioritizedBeanDefinitionRegistryPostProcessor.class));
 		}
-
-		@Override
-		public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
-		}
 	}