Introduce alias for 'value' attribute in @ComponentScan.Filter

Issue: SPR-11393

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

@@ -157,10 +157,18 @@ public @interface ComponentScan {
 		/**
 		 * The type of filter to use.
 		 * <p>Default is {@link FilterType#ANNOTATION}.
+		 * @see #classes
 		 * @see #pattern
 		 */
 		FilterType type() default FilterType.ANNOTATION;
 
+		/**
+		 * Alias for {@link #classes}.
+		 * @see #classes
+		 */
+		@AliasFor(attribute = "classes")
+		Class<?>[] value() default {};
+
 		/**
 		 * The class or classes to use as the filter.
 		 * <p>The following table explains how the classes will be interpreted
@@ -178,8 +186,12 @@ public @interface ComponentScan {
 		 * &mdash; for example, "include types annotated with {@code @Foo} OR {@code @Bar}".
 		 * <p>Specifying zero classes is permitted but will have no effect on component
 		 * scanning.
+		 * @since 4.2
+		 * @see #value
+		 * @see #type
 		 */
-		Class<?>[] value() default {};
+		@AliasFor(attribute = "value")
+		Class<?>[] classes() default {};
 
 		/**
 		 * The pattern (or patterns) to use for the filter, as an alternative

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2015 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.
@@ -47,6 +47,7 @@ import org.springframework.util.StringUtils;
  *
  * @author Chris Beams
  * @author Juergen Hoeller
+ * @author Sam Brannen
  * @since 3.1
  * @see ClassPathBeanDefinitionScanner#scan(String...)
  * @see ComponentScanBeanDefinitionParser
@@ -73,13 +74,12 @@ class ComponentScanAnnotationParser {
 
 
 	public Set<BeanDefinitionHolder> parse(AnnotationAttributes componentScan, final String declaringClass) {
+		Assert.state(this.environment != null, "Environment must not be null");
+		Assert.state(this.resourceLoader != null, "ResourceLoader must not be null");
+
 		ClassPathBeanDefinitionScanner scanner =
 				new ClassPathBeanDefinitionScanner(this.registry, componentScan.getBoolean("useDefaultFilters"));
-
-		Assert.notNull(this.environment, "Environment must not be null");
 		scanner.setEnvironment(this.environment);
-
-		Assert.notNull(this.resourceLoader, "ResourceLoader must not be null");
 		scanner.setResourceLoader(this.resourceLoader);
 
 		Class<? extends BeanNameGenerator> generatorClass = componentScan.getClass("nameGenerator");
@@ -141,7 +141,7 @@ class ComponentScanAnnotationParser {
 		List<TypeFilter> typeFilters = new ArrayList<TypeFilter>();
 		FilterType filterType = filterAttributes.getEnum("type");
 
-		for (Class<?> filterClass : filterAttributes.getClassArray("value")) {
+		for (Class<?> filterClass : filterAttributes.getAliasedClassArray("classes", ComponentScan.Filter.class, null)) {
 			switch (filterType) {
 				case ANNOTATION:
 					Assert.isAssignable(Annotation.class, filterClass,

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

@@ -296,11 +296,12 @@ class MyScopeMetadataResolver extends AnnotationScopeMetadataResolver {
 }
 
 @Configuration
-@ComponentScan(basePackages="org.springframework.context.annotation",
+@ComponentScan(
+		basePackages="org.springframework.context.annotation",
 		useDefaultFilters=false,
-		includeFilters=@Filter(type=FilterType.CUSTOM, value=ComponentScanParserTests.CustomTypeFilter.class),
+		includeFilters = @Filter(type = FilterType.CUSTOM, classes = ComponentScanParserTests.CustomTypeFilter.class),
 		// exclude this class from scanning since it's in the scanned package
-		excludeFilters=@Filter(type=FilterType.ASSIGNABLE_TYPE, value=ComponentScanWithCustomTypeFilter.class),
+		excludeFilters = @Filter(type = FilterType.ASSIGNABLE_TYPE, classes = ComponentScanWithCustomTypeFilter.class),
 		lazyInit = true)
 class ComponentScanWithCustomTypeFilter {
 	@Bean
@@ -320,7 +321,7 @@ class ComponentScanWithCustomTypeFilter {
 @ComponentScan(basePackages="example.scannable",
 		scopedProxy=ScopedProxyMode.INTERFACES,
 		useDefaultFilters=false,
-		includeFilters=@Filter(type=FilterType.ASSIGNABLE_TYPE, value=ScopedProxyTestBean.class))
+		includeFilters = @Filter(type = FilterType.ASSIGNABLE_TYPE, classes = ScopedProxyTestBean.class))
 class ComponentScanWithScopedProxy {}
 
 @Configuration