Improve exception for mixed explicit/implicit aliases with @AliasFor

Given the following improperly configured composed @RequestMapping
annotation:

@retention(RetentionPolicy.RUNTIME)
@RequestMapping
@interface PostApi {

	@AliasFor("value")
	String[] path() default {};

	@AliasFor(annotation = RequestMapping.class, attribute = "path")
	String[] value() default {};
}

Prior to this commit, an attempt to process the above annotation
resulted in an exception similar to the following, which is not
especially helpful to discern the problem.

> Attribute 'value' in annotation [PostApi] must be declared as an
> @AliasFor 'path', not 'path'.

This commit improves the exception message for such scenarios,
resulting in an exception message similar to the following.

> Attribute 'value' in annotation [PostApi] must be declared as an
> @AliasFor attribute 'path' in annotation [PostApi], not attribute
> 'path' in annotation [RequestMapping].

Closes gh-24168

spring-core/src/main/java/org/springframework/core/annotation/AnnotationTypeMapping.java

@@ -182,9 +182,9 @@ private Method resolveAliasTarget(Method attribute, AliasFor aliasFor, boolean c
 				Method mirror = resolveAliasTarget(target, targetAliasFor, false);
 				if (!mirror.equals(attribute)) {
 					throw new AnnotationConfigurationException(String.format(
-							"%s must be declared as an @AliasFor '%s', not '%s'.",
+							"%s must be declared as an @AliasFor %s, not %s.",
 							StringUtils.capitalize(AttributeMethods.describe(target)),
-							attribute.getName(), mirror.getName()));
+							AttributeMethods.describe(attribute), AttributeMethods.describe(mirror)));
 				}
 			}
 		}

spring-core/src/test/java/org/springframework/core/annotation/AnnotationTypeMappingsTests.java

@@ -160,11 +160,28 @@ void forAnnotationTypeWhenAliasForWithIncompatibleReturnTypes() {
 
 	@Test
 	void forAnnotationTypeWhenAliasForToSelfAnnotatedToOtherAttribute() {
-		assertThatExceptionOfType(AnnotationConfigurationException.class).isThrownBy(() ->
-				AnnotationTypeMappings.forAnnotationType(AliasForToSelfAnnotatedToOtherAttribute.class))
-			.withMessage("Attribute 'b' in annotation ["
-								+ AliasForToSelfAnnotatedToOtherAttribute.class.getName()
-								+ "] must be declared as an @AliasFor 'a', not 'c'.");
+		String annotationType = AliasForToSelfAnnotatedToOtherAttribute.class.getName();
+		assertThatExceptionOfType(AnnotationConfigurationException.class)
+				.isThrownBy(() -> AnnotationTypeMappings.forAnnotationType(AliasForToSelfAnnotatedToOtherAttribute.class))
+				.withMessage("Attribute 'b' in annotation [" + annotationType
+						+ "] must be declared as an @AliasFor attribute 'a' in annotation [" + annotationType
+						+ "], not attribute 'c' in annotation [" + annotationType + "].");
+	}
+
+	@Test
+	void forAnnotationTypeWhenAliasForHasMixedImplicitAndExplicitAliases() {
+		assertMixedImplicitAndExplicitAliases(AliasForWithMixedImplicitAndExplicitAliasesV1.class, "b");
+		assertMixedImplicitAndExplicitAliases(AliasForWithMixedImplicitAndExplicitAliasesV2.class, "a");
+	}
+
+	private void assertMixedImplicitAndExplicitAliases(Class<? extends Annotation> annotationType, String overriddenAttribute) {
+		String annotationName = annotationType.getName();
+		String metaAnnotationName = AliasPair.class.getName();
+		assertThatExceptionOfType(AnnotationConfigurationException.class)
+				.isThrownBy(() -> AnnotationTypeMappings.forAnnotationType(annotationType))
+				.withMessage("Attribute 'b' in annotation [" + annotationName
+						+ "] must be declared as an @AliasFor attribute 'a' in annotation [" + annotationName
+						+ "], not attribute '" + overriddenAttribute + "' in annotation [" + metaAnnotationName + "].");
 	}
 
 	@Test
@@ -641,6 +658,42 @@ private Object extractFromMap(Method attribute, Object map) {
 		String c() default "";
 	}
 
+	@Retention(RetentionPolicy.RUNTIME)
+	@interface AliasPair {
+
+		@AliasFor("b")
+		String a() default "";
+
+		@AliasFor("a")
+		String b() default "";
+	}
+
+	@Retention(RetentionPolicy.RUNTIME)
+	@AliasPair
+	@interface AliasForWithMixedImplicitAndExplicitAliasesV1 {
+
+		// attempted implicit alias via attribute override
+		@AliasFor(annotation = AliasPair.class, attribute = "b")
+		String b() default "";
+
+		// explicit local alias
+		@AliasFor("b")
+		String a() default "";
+	}
+
+	@Retention(RetentionPolicy.RUNTIME)
+	@AliasPair
+	@interface AliasForWithMixedImplicitAndExplicitAliasesV2 {
+
+		// attempted implicit alias via attribute override
+		@AliasFor(annotation = AliasPair.class, attribute = "a")
+		String b() default "";
+
+		// explicit local alias
+		@AliasFor("b")
+		String a() default "";
+	}
+
 	@Retention(RetentionPolicy.RUNTIME)
 	@interface AliasForNonMetaAnnotated {
 
@@ -712,16 +765,6 @@ private Object extractFromMap(Method attribute, Object map) {
 		String alias() default "";
 	}
 
-	@Retention(RetentionPolicy.RUNTIME)
-	@interface AliasPair {
-
-		@AliasFor("b")
-		String a() default "";
-
-		@AliasFor("a")
-		String b() default "";
-	}
-
 	@Retention(RetentionPolicy.RUNTIME)
 	@interface ImplicitMirrorsTarget {