Add regression test for type variable collision across interfaces

spring-core/src/test/java/org/springframework/core/GenericTypeResolverTests.java

@@ -250,6 +250,16 @@ void resolveTypeFromGenericDefaultMethod() {
 		assertThat(resolvedType).isEqualTo(InheritsDefaultMethod.ConcreteType.class);
 	}
 
+	@Test
+	void resolveTypeVariableCollisionAcrossInterfaces() throws Exception {
+		Type createBody = Create.class.getMethod("create", Object.class)
+				.getGenericParameterTypes()[0];
+
+		Type resolved = resolveType(createBody, Controller.class);
+
+		assertThat(resolved).isEqualTo(Long.class);
+	}
+
 	private static Method method(Class<?> target, String methodName, Class<?>... parameterTypes) {
 		Method method = findMethod(target, methodName, parameterTypes);
 		assertThat(method).describedAs(target.getName() + "#" + methodName).isNotNull();
@@ -477,4 +487,17 @@ static class ConcreteType implements InterfaceWithDefaultMethod.AbstractType {
 		}
 	}
 
+	interface Search<I, O> {
+	}
+
+	interface Create<I, O> {
+
+		default O create(I body) {
+			return null;
+		}
+	}
+
+	static class Controller implements Search<String, Long>, Create<Long, Long> {
+	}
+
 }