Support annotation attribute aliases and overrides via @AliasFor

This commit introduces first-class support for aliases for annotation
attributes. Specifically, this commit introduces a new @AliasFor
annotation that can be used to declare a pair of aliased attributes
within a single annotation or an alias from an attribute in a custom
composed annotation to an attribute in a meta-annotation.

To support @AliasFor within annotation instances, AnnotationUtils has
been overhauled to "synthesize" any annotations returned by "get" and
"find" searches. A SynthesizedAnnotation is an annotation that is
wrapped in a JDK dynamic proxy which provides run-time support for
@AliasFor semantics. SynthesizedAnnotationInvocationHandler is the
actual handler behind the proxy.

In addition, the contract for @AliasFor is fully validated, and an
AnnotationConfigurationException is thrown in case invalid
configuration is detected.

For example, @ContextConfiguration from the spring-test module is now
declared as follows:

    public @interface ContextConfiguration {

        @AliasFor(attribute = "locations")
        String[] value() default {};

        @AliasFor(attribute = "value")
        String[] locations() default {};

        // ...
    }

The following annotations and their related support classes have been
modified to use @AliasFor.

- @ManagedResource
- @ContextConfiguration
- @ActiveProfiles
- @TestExecutionListeners
- @TestPropertySource
- @Sql
- @ControllerAdvice
- @RequestMapping

Similarly, support for AnnotationAttributes has been reworked to
support @AliasFor as well. This allows for fine-grained control over
exactly which attributes are overridden within an annotation hierarchy.
In fact, it is now possible to declare an alias for the 'value'
attribute of a meta-annotation.

For example, given the revised declaration of @ContextConfiguration
above, one can now develop a composed annotation with a custom
attribute override as follows.

    @ContextConfiguration
    public @interface MyTestConfig {

        @AliasFor(
           annotation = ContextConfiguration.class,
           attribute = "locations"
        )
        String[] xmlFiles();

        // ...
    }

Consequently, the following are functionally equivalent.

- @MyTestConfig(xmlFiles = "test.xml")
- @ContextConfiguration("test.xml")
- @ContextConfiguration(locations = "test.xml").

Issue: SPR-11512, SPR-11513

spring-web/src/main/java/org/springframework/web/bind/annotation/ControllerAdvice.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.
@@ -23,6 +23,7 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+import org.springframework.core.annotation.AliasFor;
 import org.springframework.stereotype.Component;
 
 /**
@@ -50,6 +51,7 @@ import org.springframework.stereotype.Component;
  *
  * @author Rossen Stoyanchev
  * @author Brian Clozel
+ * @author Sam Brannen
  * @since 3.2
  */
 @Target(ElementType.TYPE)
@@ -59,26 +61,28 @@ import org.springframework.stereotype.Component;
 public @interface ControllerAdvice {
 
 	/**
-	 * Alias for the {@link #basePackages()} attribute.
-	 * Allows for more concise annotation declarations e.g.:
+	 * Alias for the {@link #basePackages} attribute.
+	 * <p>Allows for more concise annotation declarations e.g.:
 	 * {@code @ControllerAdvice("org.my.pkg")} is equivalent to
 	 * {@code @ControllerAdvice(basePackages="org.my.pkg")}.
 	 * @since 4.0
 	 * @see #basePackages()
 	 */
+	@AliasFor(attribute = "basePackages")
 	String[] value() default {};
 
 	/**
 	 * Array of base packages.
-	 * Controllers that belong to those base packages or sub-packages thereof
+	 * <p>Controllers that belong to those base packages or sub-packages thereof
 	 * will be included, e.g.: {@code @ControllerAdvice(basePackages="org.my.pkg")}
 	 * or {@code @ControllerAdvice(basePackages={"org.my.pkg", "org.my.other.pkg"})}.
-	 * <p>{@link #value()} is an alias for this attribute, simply allowing for
+	 * <p>{@link #value} is an alias for this attribute, simply allowing for
 	 * more concise use of the annotation.
 	 * <p>Also consider using {@link #basePackageClasses()} as a type-safe
 	 * alternative to String-based package names.
 	 * @since 4.0
 	 */
+	@AliasFor(attribute = "value")
 	String[] basePackages() default {};
 
 	/**
@@ -93,7 +97,7 @@ public @interface ControllerAdvice {
 
 	/**
 	 * Array of classes.
-	 * Controllers that are assignable to at least one of the given types
+	 * <p>Controllers that are assignable to at least one of the given types
 	 * will be assisted by the {@code @ControllerAdvice} annotated class.
 	 * @since 4.0
 	 */
@@ -101,7 +105,7 @@ public @interface ControllerAdvice {
 
 	/**
 	 * Array of annotations.
-	 * Controllers that are annotated with this/one of those annotation(s)
+	 * <p>Controllers that are annotated with this/one of those annotation(s)
 	 * will be assisted by the {@code @ControllerAdvice} annotated class.
 	 * <p>Consider creating a special annotation or use a predefined one,
 	 * like {@link RestController @RestController}.

spring-web/src/main/java/org/springframework/web/bind/annotation/RequestMapping.java

@@ -23,6 +23,8 @@ import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 import java.util.concurrent.Callable;
 
+import org.springframework.core.annotation.AliasFor;
+
 /**
  * Annotation for mapping web requests onto specific handler classes and/or
  * handler methods. Provides a consistent style between Servlet and Portlet
@@ -298,7 +300,7 @@ public @interface RequestMapping {
 
 	/**
 	 * The primary mapping expressed by this annotation.
-	 * <p>In a Servlet environment this is an alias for {@link #path()}.
+	 * <p>In a Servlet environment this is an alias for {@link #path}.
 	 * For example {@code @RequestMapping("/foo")} is equivalent to
 	 * {@code @RequestMapping(path="/foo")}.
 	 * <p>In a Portlet environment this is the mapped portlet modes
@@ -307,6 +309,7 @@ public @interface RequestMapping {
 	 * When used at the type level, all method-level mappings inherit
 	 * this primary mapping, narrowing it for a specific handler method.
 	 */
+	@AliasFor(attribute = "path")
 	String[] value() default {};
 
 	/**
@@ -321,6 +324,7 @@ public @interface RequestMapping {
 	 * @see org.springframework.web.bind.annotation.ValueConstants#DEFAULT_NONE
 	 * @since 4.2
 	 */
+	@AliasFor(attribute = "value")
 	String[] path() default {};
 
 	/**

spring-web/src/main/java/org/springframework/web/method/ControllerAdviceBean.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.
@@ -223,11 +223,6 @@ public class ControllerAdviceBean implements Ordered {
 
 	private static Set<String> initBasePackages(ControllerAdvice annotation) {
 		Set<String> basePackages = new LinkedHashSet<String>();
-		for (String basePackage : annotation.value()) {
-			if (StringUtils.hasText(basePackage)) {
-				basePackages.add(adaptBasePackage(basePackage));
-			}
-		}
 		for (String basePackage : annotation.basePackages()) {
 			if (StringUtils.hasText(basePackage)) {
 				basePackages.add(adaptBasePackage(basePackage));