Find annotation on overridden method in type hierarchy with unresolved generics

Prior to this commit, the MergedAnnotations support (specifically
AnnotationsScanner) and AnnotatedMethod did not find annotations on
overridden methods in type hierarchies with unresolved generics.

The reason for this is that ResolvableType.resolve() returns null for
such an unresolved type, which prevents the search algorithms from
considering such methods as override candidates.

For example, given the following type hierarchy, the compiler does not
generate a method corresponding to processOneAndTwo(Long, String) for
GenericInterfaceImpl. Nonetheless, one would expect an invocation of
processOneAndTwo(Long, String) to be @⁠Transactional since it is
effectively an invocation of processOneAndTwo(Long, C) in
GenericAbstractSuperclass, which overrides/implements
processOneAndTwo(A, B) in GenericInterface, which is annotated with
@⁠Transactional.

However, the MergedAnnotations infrastructure currently does not
determine that processOneAndTwo(Long, C) is @⁠Transactional since it is
not able to determine that processOneAndTwo(Long, C) overrides
processOneAndTwo(A, B) because of the unresolved generic C.

interface GenericInterface<A, B> {

    @⁠Transactional
    void processOneAndTwo(A value1, B value2);
}

abstract class GenericAbstractSuperclass<C> implements GenericInterface<Long, C> {

    @⁠Override
    public void processOneAndTwo(Long value1, C value2) {
    }
}

static GenericInterfaceImpl extends GenericAbstractSuperclass<String> {
}

To address such issues, this commit changes the logic in
AnnotationsScanner.hasSameGenericTypeParameters() and
AnnotatedMethod.isOverrideFor() so that they use
ResolvableType.toClass() instead of ResolvableType.resolve(). The
former returns Object.class for an unresolved generic which in turn
allows the search algorithms to properly detect method overrides in
such type hierarchies.

Closes spring-projectsgh-35342

Author: sbrannen

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

@@ -386,7 +386,7 @@ private static boolean hasSameGenericTypeParameters(
 		}
 		for (int i = 0; i < rootParameterTypes.length; i++) {
 			Class<?> resolvedParameterType = ResolvableType.forMethodParameter(
-					candidateMethod, i, sourceDeclaringClass).resolve();
+					candidateMethod, i, sourceDeclaringClass).toClass();
 			if (rootParameterTypes[i] != resolvedParameterType) {
 				return false;
 			}

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

@@ -831,6 +831,15 @@ void getFromMethodWithGenericSuperclass() throws Exception {
 				Order.class).getDistance()).isEqualTo(0);
 	}
 
+	@Test
+	void getFromMethodWithUnresolvedGenericsInGenericTypeHierarchy() {
+		// The following method is GenericAbstractSuperclass.processOneAndTwo(java.lang.Long, C),
+		// where 'C' is an unresolved generic, for which ResolvableType.resolve() returns null.
+		Method method = ClassUtils.getMethod(GenericInterfaceImpl.class, "processOneAndTwo", Long.class, Object.class);
+		assertThat(MergedAnnotations.from(method, SearchStrategy.TYPE_HIERARCHY)
+				.get(Transactional.class).isDirectlyPresent()).isTrue();
+	}
+
 	@Test
 	void getFromMethodWithInterfaceOnSuper() throws Exception {
 		Method method = SubOfImplementsInterfaceWithAnnotatedMethod.class.getMethod("foo");
@@ -2882,6 +2891,26 @@ public void foo(String t) {
 		}
 	}
 
+	interface GenericInterface<A, B> {
+
+		@Transactional
+		void processOneAndTwo(A value1, B value2);
+	}
+
+	abstract static class GenericAbstractSuperclass<C> implements GenericInterface<Long, C> {
+
+		@Override
+		public void processOneAndTwo(Long value1, C value2) {
+		}
+	}
+
+	static class GenericInterfaceImpl extends GenericAbstractSuperclass<String> {
+		// The compiler does not require us to declare a concrete
+		// processOneAndTwo(Long, String) method, and we intentionally
+		// do not declare one here.
+	}
+
+
 	@Retention(RetentionPolicy.RUNTIME)
 	@Inherited
 	@interface MyRepeatableContainer {

spring-web/src/main/java/org/springframework/web/method/HandlerMethod.java

@@ -416,7 +416,7 @@ private boolean isOverrideFor(Method candidate) {
 		}
 		for (int i = 0; i < paramTypes.length; i++) {
 			if (paramTypes[i] !=
-					ResolvableType.forMethodParameter(candidate, i, this.method.getDeclaringClass()).resolve()) {
+					ResolvableType.forMethodParameter(candidate, i, this.method.getDeclaringClass()).toClass()) {
 				return false;
 			}
 		}