@Import detects and accepts existing configuration class in any order of processing

org.springframework.context/src/main/java/org/springframework/context/annotation/ConfigurationClass.java

@@ -34,9 +34,7 @@ import org.springframework.util.ClassUtils;
 /**
  * Represents a user-defined {@link Configuration @Configuration} class.
  * Includes a set of {@link Bean} methods, including all such methods defined in the
- * ancestry of the class, in a 'flattened-out' manner. Note that each {@link ConfigurationClassMethod}
- * representation contains source information about where it was originally detected
- * (for the purpose of tooling with Spring IDE).
+ * ancestry of the class, in a 'flattened-out' manner.
  *
  * @author Chris Beams
  * @author Juergen Hoeller
@@ -131,14 +129,8 @@ final class ConfigurationClass {
 
 	@Override
 	public boolean equals(Object other) {
-		if (this == other) {
-			return true;
-		}
-		if (!(other instanceof ConfigurationClass)) {
-			return false;
-		}
-		ConfigurationClass otherCc = (ConfigurationClass) other;
-		return getMetadata().getClassName().equals(otherCc.getMetadata().getClassName());
+		return (this == other || (other instanceof ConfigurationClass &&
+				getMetadata().getClassName().equals(((ConfigurationClass) other).getMetadata().getClassName())));
 	}
 
 	@Override

org.springframework.context/src/main/java/org/springframework/context/annotation/ConfigurationClassBeanDefinitionReader.java

@@ -51,6 +51,7 @@ import org.springframework.util.StringUtils;
  * @author Chris Beams
  * @author Juergen Hoeller
  * @since 3.0
+ * @see ConfigurationClassParser
  */
 class ConfigurationClassBeanDefinitionReader {
 

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

@@ -37,12 +37,12 @@ import org.springframework.core.type.classreading.MetadataReaderFactory;
 
 /**
  * Parses a {@link Configuration} class definition, populating a configuration model.
- * This ASM-based implementation avoids reflection and eager classloading in order to
- * interoperate effectively with tooling (Spring IDE) and OSGi environments.
+ * This ASM-based implementation avoids reflection and eager class loading in order to
+ * interoperate effectively with lazy class loading in a Spring ApplicationContext.
  *
- * <p>This class helps separate the concern of parsing the structure of a Configuration class
- * from the concern of registering {@link BeanDefinition} objects based on the content of
- * that model.
+ * <p>This class helps separate the concern of parsing the structure of a Configuration
+ * class from the concern of registering {@link BeanDefinition} objects based on the
+ * content of that model.
  *
  * @author Chris Beams
  * @author Juergen Hoeller
@@ -112,7 +112,12 @@ class ConfigurationClassParser {
 				metadata = null;
 			}
 		}
-		model.add(configClass);
+		if (this.model.contains(configClass) && configClass.getBeanName() != null) {
+			// Explicit bean definition found, probably replacing an import.
+			// Let's remove the old one and go with the new one.
+			this.model.remove(configClass);
+		}
+		this.model.add(configClass);
 	}
 
 	protected void doProcessConfigurationClass(ConfigurationClass configClass, AnnotationMetadata metadata) throws IOException {

org.springframework.context/src/test/java/org/springframework/context/annotation/configuration/ImportTests.java

@@ -18,8 +18,10 @@ package org.springframework.context.annotation.configuration;
 
 import static org.hamcrest.CoreMatchers.*;
 import static org.junit.Assert.*;
-
 import org.junit.Test;
+import test.beans.ITestBean;
+import test.beans.TestBean;
+
 import org.springframework.beans.factory.parsing.BeanDefinitionParsingException;
 import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.beans.factory.support.RootBeanDefinition;
@@ -28,9 +30,6 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.ConfigurationClassPostProcessor;
 import org.springframework.context.annotation.Import;
 
-import test.beans.ITestBean;
-import test.beans.TestBean;
-
 
 /**
  * System tests for {@link Import} annotation support.
@@ -58,10 +57,30 @@ public class ImportTests {
 	public void testProcessImports() {
 		int configClasses = 2;
 		int beansInClasses = 2;
-
 		assertBeanDefinitionCount((configClasses + beansInClasses), ConfigurationWithImportAnnotation.class);
 	}
 
+	@Test
+	public void testProcessImportsWithDoubleImports() {
+		int configClasses = 3;
+		int beansInClasses = 3;
+		assertBeanDefinitionCount((configClasses + beansInClasses), ConfigurationWithImportAnnotation.class, OtherConfigurationWithImportAnnotation.class);
+	}
+
+	@Test
+	public void testProcessImportsWithExplicitOverridingBefore() {
+		int configClasses = 2;
+		int beansInClasses = 2;
+		assertBeanDefinitionCount((configClasses + beansInClasses), OtherConfiguration.class, ConfigurationWithImportAnnotation.class);
+	}
+
+	@Test
+	public void testProcessImportsWithExplicitOverridingAfter() {
+		int configClasses = 2;
+		int beansInClasses = 2;
+		assertBeanDefinitionCount((configClasses + beansInClasses), ConfigurationWithImportAnnotation.class, OtherConfiguration.class);
+	}
+
 	@Configuration
 	@Import(OtherConfiguration.class)
 	static class ConfigurationWithImportAnnotation {
@@ -72,13 +91,22 @@ public class ImportTests {
 	}
 
 	@Configuration
-	static class OtherConfiguration {
+	@Import(OtherConfiguration.class)
+	static class OtherConfigurationWithImportAnnotation {
 		@Bean
 		public ITestBean two() {
 			return new TestBean();
 		}
 	}
 
+	@Configuration
+	static class OtherConfiguration {
+		@Bean
+		public ITestBean three() {
+			return new TestBean();
+		}
+	}
+
 	// ------------------------------------------------------------------------
 
 	@Test