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 gh-35342

Author: sbrannen

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

@@ -204,7 +204,7 @@ 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;
 			}
 		}

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

@@ -379,7 +379,7 @@ 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/AnnotatedMethodTests.java

@@ -0,0 +1,116 @@
+/*
+ * Copyright 2002-present 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.core.annotation;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.reflect.Method;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.core.MethodParameter;
+import org.springframework.util.ClassUtils;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link AnnotatedMethod}.
+ *
+ * @author Sam Brannen
+ * @since 6.2.11
+ */
+class AnnotatedMethodTests {
+
+	@Test
+	void shouldFindAnnotationOnMethodInGenericAbstractSuperclass() {
+		Method processTwo = getMethod("processTwo", String.class);
+
+		AnnotatedMethod annotatedMethod = new AnnotatedMethod(processTwo);
+
+		assertThat(annotatedMethod.hasMethodAnnotation(Handler.class)).isTrue();
+	}
+
+	@Test
+	void shouldFindAnnotationOnMethodInGenericInterface() {
+		Method processOneAndTwo = getMethod("processOneAndTwo", Long.class, Object.class);
+
+		AnnotatedMethod annotatedMethod = new AnnotatedMethod(processOneAndTwo);
+
+		assertThat(annotatedMethod.hasMethodAnnotation(Handler.class)).isTrue();
+	}
+
+	@Test
+	void shouldFindAnnotationOnMethodParameterInGenericAbstractSuperclass() {
+		Method processTwo = getMethod("processTwo", String.class);
+
+		AnnotatedMethod annotatedMethod = new AnnotatedMethod(processTwo);
+		MethodParameter[] methodParameters = annotatedMethod.getMethodParameters();
+
+		assertThat(methodParameters).hasSize(1);
+		assertThat(methodParameters[0].hasParameterAnnotation(Param.class)).isTrue();
+	}
+
+	@Test
+	void shouldFindAnnotationOnMethodParameterInGenericInterface() {
+		Method processOneAndTwo = getMethod("processOneAndTwo", Long.class, Object.class);
+
+		AnnotatedMethod annotatedMethod = new AnnotatedMethod(processOneAndTwo);
+		MethodParameter[] methodParameters = annotatedMethod.getMethodParameters();
+
+		assertThat(methodParameters).hasSize(2);
+		assertThat(methodParameters[0].hasParameterAnnotation(Param.class)).isFalse();
+		assertThat(methodParameters[1].hasParameterAnnotation(Param.class)).isTrue();
+	}
+
+
+	private static Method getMethod(String name, Class<?>...parameterTypes) {
+		return ClassUtils.getMethod(GenericInterfaceImpl.class, name, parameterTypes);
+	}
+
+
+	@Retention(RetentionPolicy.RUNTIME)
+	@interface Handler {
+	}
+
+	@Retention(RetentionPolicy.RUNTIME)
+	@interface Param {
+	}
+
+	interface GenericInterface<A, B> {
+
+		@Handler
+		void processOneAndTwo(A value1, @Param B value2);
+	}
+
+	abstract static class GenericAbstractSuperclass<C> implements GenericInterface<Long, C> {
+
+		@Override
+		public void processOneAndTwo(Long value1, C value2) {
+		}
+
+		@Handler
+		public abstract void processTwo(@Param C value);
+	}
+
+	static class GenericInterfaceImpl extends GenericAbstractSuperclass<String> {
+
+		@Override
+		public void processTwo(String value) {
+		}
+	}
+
+}

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

@@ -945,6 +945,15 @@ 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");
@@ -3032,6 +3041,26 @@ 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/test/java/org/springframework/web/method/HandlerMethodTests.java

@@ -35,32 +35,46 @@
  * Tests for {@link HandlerMethod}.
  *
  * @author Rossen Stoyanchev
+ * @author Sam Brannen
  */
 class HandlerMethodTests {
 
 	@Test
-	void shouldValidateArgsWithConstraintsDirectlyOnClass() {
+	void shouldValidateArgsWithConstraintsDirectlyInClass() {
 		Object target = new MyClass();
 		testValidateArgs(target, List.of("addIntValue", "addPersonAndIntValue", "addPersons", "addPeople", "addNames"), true);
 		testValidateArgs(target, List.of("addPerson", "getPerson", "getIntValue", "addPersonNotValidated"), false);
 	}
 
 	@Test
-	void shouldValidateArgsWithConstraintsOnInterface() {
+	void shouldValidateArgsWithConstraintsInInterface() {
 		Object target = new MyInterfaceImpl();
 		testValidateArgs(target, List.of("addIntValue", "addPersonAndIntValue", "addPersons", "addPeople"), true);
 		testValidateArgs(target, List.of("addPerson", "addPersonNotValidated", "getPerson", "getIntValue"), false);
 	}
 
 	@Test
-	void shouldValidateReturnValueWithConstraintsDirectlyOnClass() {
+	void shouldValidateArgsWithConstraintsInGenericAbstractSuperclass() {
+		Object target = new GenericInterfaceImpl();
+		shouldValidateArguments(getHandlerMethod(target, "processTwo", String.class), true);
+	}
+
+	@Test
+	void shouldValidateArgsWithConstraintsInGenericInterface() {
+		Object target = new GenericInterfaceImpl();
+		shouldValidateArguments(getHandlerMethod(target, "processOne", Long.class), false);
+		shouldValidateArguments(getHandlerMethod(target, "processOneAndTwo", Long.class, Object.class), true);
+	}
+
+	@Test
+	void shouldValidateReturnValueWithConstraintsDirectlyInClass() {
 		Object target = new MyClass();
 		testValidateReturnValue(target, List.of("getPerson", "getIntValue"), true);
 		testValidateReturnValue(target, List.of("addPerson", "addIntValue", "addPersonNotValidated"), false);
 	}
 
 	@Test
-	void shouldValidateReturnValueWithConstraintsOnInterface() {
+	void shouldValidateReturnValueWithConstraintsInInterface() {
 		Object target = new MyInterfaceImpl();
 		testValidateReturnValue(target, List.of("getPerson", "getIntValue"), true);
 		testValidateReturnValue(target, List.of("addPerson", "addIntValue", "addPersonNotValidated"), false);
@@ -97,9 +111,19 @@ void resolvedFromHandlerMethod() {
 		assertThat(hm3.getResolvedFromHandlerMethod()).isSameAs(hm1);
 	}
 
+
+	private static void shouldValidateArguments(HandlerMethod handlerMethod, boolean expected) {
+		if (expected) {
+			assertThat(handlerMethod.shouldValidateArguments()).as(handlerMethod.getMethod().getName()).isTrue();
+		}
+		else {
+			assertThat(handlerMethod.shouldValidateArguments()).as(handlerMethod.getMethod().getName()).isFalse();
+		}
+	}
+
 	private static void testValidateArgs(Object target, List<String> methodNames, boolean expected) {
 		for (String methodName : methodNames) {
-			assertThat(getHandlerMethod(target, methodName).shouldValidateArguments()).isEqualTo(expected);
+			shouldValidateArguments(getHandlerMethod(target, methodName), expected);
 		}
 	}
 
@@ -110,7 +134,11 @@ private static void testValidateReturnValue(Object target, List<String> methodNa
 	}
 
 	private static HandlerMethod getHandlerMethod(Object target, String methodName) {
-		Method method = ClassUtils.getMethod(target.getClass(), methodName, (Class<?>[]) null);
+		return getHandlerMethod(target, methodName, (Class<?>[]) null);
+	}
+
+	private static HandlerMethod getHandlerMethod(Object target, String methodName, Class<?>... parameterTypes) {
+		Method method = ClassUtils.getMethod(target.getClass(), methodName, parameterTypes);
 		return new HandlerMethod(target, method).createWithValidateFlags();
 	}
 
@@ -236,4 +264,32 @@ public Person getPerson() {
 		}
 	}
 
+
+	interface GenericInterface<A, B> {
+
+		void processOne(@Valid A value1);
+
+		void processOneAndTwo(A value1, @Max(42) B value2);
+	}
+
+	abstract static class GenericAbstractSuperclass<C> implements GenericInterface<Long, C> {
+
+		@Override
+		public void processOne(Long value1) {
+		}
+
+		@Override
+		public void processOneAndTwo(Long value1, C value2) {
+		}
+
+		public abstract void processTwo(@Max(42) C value);
+	}
+
+	static class GenericInterfaceImpl extends GenericAbstractSuperclass<String> {
+
+		@Override
+		public void processTwo(String value) {
+		}
+	}
+
 }