ConfigurationClassParser avoids double registration of nested classes which extend their containing class

Issue: SPR-12195

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClassParser.java

@@ -311,7 +311,8 @@ class ConfigurationClassParser {
 	 */
 	private void processMemberClasses(ConfigurationClass configClass, SourceClass sourceClass) throws IOException {
 		for (SourceClass memberClass : sourceClass.getMemberClasses()) {
-			if (ConfigurationClassUtils.isConfigurationCandidate(memberClass.getMetadata())) {
+			if (ConfigurationClassUtils.isConfigurationCandidate(memberClass.getMetadata()) &&
+					!memberClass.getMetadata().getClassName().equals(configClass.getMetadata().getClassName())) {
 				processConfigurationClass(memberClass.asConfigClass(configClass));
 			}
 		}

spring-context/src/test/java/org/springframework/context/annotation/ComponentScanAnnotationIntegrationTests.java

@@ -41,6 +41,7 @@ import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.context.annotation.ComponentScan.Filter;
 import org.springframework.context.annotation.ComponentScanParserTests.KustomAnnotationAutowiredBean;
+import org.springframework.context.annotation.componentscan.simple.ClassWithNestedComponents;
 import org.springframework.context.annotation.componentscan.simple.SimpleComponent;
 import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.tests.context.SimpleMapScope;
@@ -115,6 +116,8 @@ public class ComponentScanAnnotationIntegrationTests {
 		ctx.refresh();
 		ctx.getBean(ComposedAnnotationConfig.class);
 		ctx.getBean(SimpleComponent.class);
+		ctx.getBean(ClassWithNestedComponents.NestedComponent.class);
+		ctx.getBean(ClassWithNestedComponents.OtherNestedComponent.class);
 		assertThat("config class bean not found",
 				ctx.containsBeanDefinition("componentScanAnnotationIntegrationTests.ComposedAnnotationConfig"), is(true));
 		assertThat("@ComponentScan annotated @Configuration class registered directly against " +

spring-context/src/test/java/org/springframework/context/annotation/componentscan/simple/ClassWithNestedComponents.java

@@ -0,0 +1,31 @@
+/*
+ * Copyright 2002-2014 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.context.annotation.componentscan.simple;
+
+import org.springframework.stereotype.Component;
+
+public class ClassWithNestedComponents {
+
+	@Component
+	public static class NestedComponent extends ClassWithNestedComponents {
+	}
+
+	@Component
+	public static class OtherNestedComponent extends ClassWithNestedComponents {
+	}
+
+}