Remove redundant Assert.notNull() checks in ResolvableType

Since equivalent Assert.notNull() checks are already performed by
subsequent code (constructors and factory methods), there is no need
to perform the exact same assertion twice in such use cases.

Closes gh-36544

Author: sbrannen

spring-core/src/main/java/org/springframework/core/ResolvableType.java

@@ -1152,7 +1152,6 @@ public static ResolvableType forClass(Class<?> baseType, Class<?> implementation
 	 * @see #forClassWithGenerics(Class, ResolvableType...)
 	 */
 	public static ResolvableType forClassWithGenerics(Class<?> clazz, Class<?>... generics) {
-		Assert.notNull(clazz, "Class must not be null");
 		Assert.notNull(generics, "Generics array must not be null");
 		ResolvableType[] resolvableGenerics = new ResolvableType[generics.length];
 		for (int i = 0; i < generics.length; i++) {
@@ -1289,7 +1288,6 @@ public static ResolvableType forField(Field field, int nestingLevel, @Nullable C
 	 * @see #forConstructorParameter(Constructor, int, Class)
 	 */
 	public static ResolvableType forConstructorParameter(Constructor<?> constructor, int parameterIndex) {
-		Assert.notNull(constructor, "Constructor must not be null");
 		return forMethodParameter(new MethodParameter(constructor, parameterIndex));
 	}
 
@@ -1307,7 +1305,6 @@ public static ResolvableType forConstructorParameter(Constructor<?> constructor,
 	public static ResolvableType forConstructorParameter(Constructor<?> constructor, int parameterIndex,
 			Class<?> implementationClass) {
 
-		Assert.notNull(constructor, "Constructor must not be null");
 		MethodParameter methodParameter = new MethodParameter(constructor, parameterIndex, implementationClass);
 		return forMethodParameter(methodParameter);
 	}
@@ -1319,7 +1316,6 @@ public static ResolvableType forConstructorParameter(Constructor<?> constructor,
 	 * @see #forMethodReturnType(Method, Class)
 	 */
 	public static ResolvableType forMethodReturnType(Method method) {
-		Assert.notNull(method, "Method must not be null");
 		return forMethodParameter(new MethodParameter(method, -1));
 	}
 
@@ -1333,7 +1329,6 @@ public static ResolvableType forMethodReturnType(Method method) {
 	 * @see #forMethodReturnType(Method)
 	 */
 	public static ResolvableType forMethodReturnType(Method method, Class<?> implementationClass) {
-		Assert.notNull(method, "Method must not be null");
 		MethodParameter methodParameter = new MethodParameter(method, -1, implementationClass);
 		return forMethodParameter(methodParameter);
 	}
@@ -1347,7 +1342,6 @@ public static ResolvableType forMethodReturnType(Method method, Class<?> impleme
 	 * @see #forMethodParameter(MethodParameter)
 	 */
 	public static ResolvableType forMethodParameter(Method method, int parameterIndex) {
-		Assert.notNull(method, "Method must not be null");
 		return forMethodParameter(new MethodParameter(method, parameterIndex));
 	}
 
@@ -1363,7 +1357,6 @@ public static ResolvableType forMethodParameter(Method method, int parameterInde
 	 * @see #forMethodParameter(MethodParameter)
 	 */
 	public static ResolvableType forMethodParameter(Method method, int parameterIndex, Class<?> implementationClass) {
-		Assert.notNull(method, "Method must not be null");
 		MethodParameter methodParameter = new MethodParameter(method, parameterIndex, implementationClass);
 		return forMethodParameter(methodParameter);
 	}

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

@@ -221,6 +221,13 @@ void forConstructorParameterMustNotBeNull() {
 				.withMessage("Constructor must not be null");
 	}
 
+	@Test
+	void forConstructorParameterWithImplementationClassMustNotBeNull() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> ResolvableType.forConstructorParameter(null, 0, TypedConstructors.class))
+				.withMessage("Executable must not be null");
+	}
+
 	@Test
 	void forMethodParameterByIndex() throws Exception {
 		Method method = Methods.class.getMethod("charSequenceParameter", List.class);
@@ -235,6 +242,13 @@ void forMethodParameterByIndexMustNotBeNull() {
 				.withMessage("Method must not be null");
 	}
 
+	@Test
+	void forMethodParameterByIndexWithImplementationClassMustNotBeNull() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> ResolvableType.forMethodParameter(null, 0, TypedMethods.class))
+				.withMessage("Executable must not be null");
+	}
+
 	@Test
 	void forMethodParameter() throws Exception {
 		Method method = Methods.class.getMethod("charSequenceParameter", List.class);
@@ -302,6 +316,13 @@ void forMethodReturnMustNotBeNull() {
 				.withMessage("Method must not be null");
 	}
 
+	@Test
+	void forMethodReturnWithImplementationClassMustNotBeNull() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> ResolvableType.forMethodReturnType(null, TypedMethods.class))
+				.withMessage("Executable must not be null");
+	}
+
 	@Test  // gh-27748
 	void genericMatchesReturnType() throws Exception {
 		Method method = SomeRepository.class.getMethod("someMethod", Class.class, Class.class, Class.class);
@@ -1307,6 +1328,13 @@ void classWithGenericsAs() {
 		assertThat(type.asMap().toString()).isEqualTo("java.util.Map<java.lang.Integer, java.util.List<java.lang.String>>");
 	}
 
+	@Test
+	void forClassWithGenericsClassMustNotBeNull() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> ResolvableType.forClassWithGenerics(null, String.class))
+				.withMessage("Class must not be null");
+	}
+
 	@Test
 	void forClassWithMismatchedGenerics() {
 		assertThatIllegalArgumentException()