Specify generic type nullness in spring-aop

See spring-projectsgh-34140

Author: sdeleuze

Diff for: spring-aop/src/main/java/org/springframework/aop/AfterReturningAdvice.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -41,6 +41,6 @@ public interface AfterReturningAdvice extends AfterAdvice {
 	 * allowed by the method signature. Otherwise the exception
 	 * will be wrapped as a runtime exception.
 	 */
-	void afterReturning(@Nullable Object returnValue, Method method, Object[] args, @Nullable Object target) throws Throwable;
+	void afterReturning(@Nullable Object returnValue, Method method, @Nullable Object[] args, @Nullable Object target) throws Throwable;
 
 }

Diff for: spring-aop/src/main/java/org/springframework/aop/MethodBeforeAdvice.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -40,6 +40,6 @@ public interface MethodBeforeAdvice extends BeforeAdvice {
 	 * allowed by the method signature. Otherwise the exception
 	 * will be wrapped as a runtime exception.
 	 */
-	void before(Method method, Object[] args, @Nullable Object target) throws Throwable;
+	void before(Method method, @Nullable Object[] args, @Nullable Object target) throws Throwable;
 
 }

Diff for: spring-aop/src/main/java/org/springframework/aop/aspectj/AbstractAspectJAdvice.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -43,6 +43,7 @@
 import org.springframework.aop.support.StaticMethodMatcher;
 import org.springframework.core.DefaultParameterNameDiscoverer;
 import org.springframework.core.ParameterNameDiscoverer;
+import org.springframework.lang.Contract;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.CollectionUtils;
@@ -258,10 +259,11 @@ public void setArgumentNames(String argumentNames) {
 	 * or in an advice annotation.
 	 * @param argumentNames list of argument names
 	 */
-	public void setArgumentNamesFromStringArray(String... argumentNames) {
+	public void setArgumentNamesFromStringArray(@Nullable String... argumentNames) {
 		this.argumentNames = new String[argumentNames.length];
 		for (int i = 0; i < argumentNames.length; i++) {
-			this.argumentNames[i] = argumentNames[i].strip();
+			String argumentName = argumentNames[i];
+			this.argumentNames[i] = argumentName != null ? argumentName.strip() : null;
 			if (!isVariableName(this.argumentNames[i])) {
 				throw new IllegalArgumentException(
 						"'argumentNames' property of AbstractAspectJAdvice contains an argument name '" +
@@ -274,7 +276,7 @@ public void setArgumentNamesFromStringArray(String... argumentNames) {
 			if (firstArgType == JoinPoint.class ||
 					firstArgType == ProceedingJoinPoint.class ||
 					firstArgType == JoinPoint.StaticPart.class) {
-				String[] oldNames = this.argumentNames;
+				@Nullable String[] oldNames = this.argumentNames;
 				this.argumentNames = new String[oldNames.length + 1];
 				this.argumentNames[0] = "THIS_JOIN_POINT";
 				System.arraycopy(oldNames, 0, this.argumentNames, 1, oldNames.length);
@@ -346,7 +348,8 @@ protected Class<?> getDiscoveredThrowingType() {
 		return this.discoveredThrowingType;
 	}
 
-	private static boolean isVariableName(String name) {
+	@Contract("null -> false")
+	private static boolean isVariableName(@Nullable String name) {
 		return AspectJProxyUtils.isVariableName(name);
 	}
 
@@ -456,6 +459,7 @@ protected ParameterNameDiscoverer createParameterNameDiscoverer() {
 		return discoverer;
 	}
 
+	@SuppressWarnings("NullAway") // Dataflow analysis limitation
 	private void bindExplicitArguments(int numArgumentsLeftToBind) {
 		Assert.state(this.argumentNames != null, "No argument names available");
 		this.argumentBindings = new HashMap<>();
@@ -623,8 +627,8 @@ protected Object invokeAdviceMethod(JoinPoint jp, @Nullable JoinPointMatch jpMat
 		return invokeAdviceMethodWithGivenArgs(argBinding(jp, jpMatch, returnValue, t));
 	}
 
-	protected Object invokeAdviceMethodWithGivenArgs(Object[] args) throws Throwable {
-		Object[] actualArgs = args;
+	protected Object invokeAdviceMethodWithGivenArgs(@Nullable Object[] args) throws Throwable {
+		@Nullable Object[] actualArgs = args;
 		if (this.aspectJAdviceMethod.getParameterCount() == 0) {
 			actualArgs = null;
 		}

Diff for: spring-aop/src/main/java/org/springframework/aop/aspectj/AspectJAfterReturningAdvice.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -62,7 +62,7 @@ public void setReturningName(String name) {
 	}
 
 	@Override
-	public void afterReturning(@Nullable Object returnValue, Method method, Object[] args, @Nullable Object target) throws Throwable {
+	public void afterReturning(@Nullable Object returnValue, Method method, @Nullable Object[] args, @Nullable Object target) throws Throwable {
 		if (shouldInvokeOnReturnValueOf(method, returnValue)) {
 			invokeAdviceMethod(getJoinPointMatch(), returnValue, null);
 		}

Diff for: spring-aop/src/main/java/org/springframework/aop/aspectj/AspectJMethodBeforeAdvice.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -41,7 +41,7 @@ public AspectJMethodBeforeAdvice(
 
 
 	@Override
-	public void before(Method method, Object[] args, @Nullable Object target) throws Throwable {
+	public void before(Method method, @Nullable Object[] args, @Nullable Object target) throws Throwable {
 		invokeAdviceMethod(getJoinPointMatch(), null, null);
 	}
 

Diff for: spring-aop/src/main/java/org/springframework/aop/aspectj/AspectJProxyUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2022 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -23,6 +23,7 @@
 import org.springframework.aop.Advisor;
 import org.springframework.aop.PointcutAdvisor;
 import org.springframework.aop.interceptor.ExposeInvocationInterceptor;
+import org.springframework.lang.Contract;
 import org.springframework.util.StringUtils;
 
 /**
@@ -76,6 +77,7 @@ private static boolean isAspectJAdvice(Advisor advisor) {
 						pointcutAdvisor.getPointcut() instanceof AspectJExpressionPointcut));
 	}
 
+	@Contract("null -> false")
 	static boolean isVariableName(@Nullable String name) {
 		if (!StringUtils.hasLength(name)) {
 			return false;

Diff for: spring-aop/src/main/java/org/springframework/aop/aspectj/MethodInvocationProceedingJoinPoint.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -55,7 +55,7 @@ public class MethodInvocationProceedingJoinPoint implements ProceedingJoinPoint,
 
 	private final ProxyMethodInvocation methodInvocation;
 
-	private Object @Nullable [] args;
+	private @Nullable Object @Nullable [] args;
 
 	/** Lazily initialized signature object. */
 	private @Nullable Signature signature;
@@ -114,7 +114,8 @@ public Object getThis() {
 	}
 
 	@Override
-	public Object[] getArgs() {
+	@SuppressWarnings("NullAway") // Overridden method does not define nullness
+	public @Nullable Object[] getArgs() {
 		if (this.args == null) {
 			this.args = this.methodInvocation.getArguments().clone();
 		}
@@ -174,7 +175,7 @@ public String toString() {
 	 */
 	private class MethodSignatureImpl implements MethodSignature {
 
-		private volatile String @Nullable [] parameterNames;
+		private volatile @Nullable String @Nullable [] parameterNames;
 
 		@Override
 		public String getName() {
@@ -212,8 +213,9 @@ public Class<?>[] getParameterTypes() {
 		}
 
 		@Override
-		public String @Nullable [] getParameterNames() {
-			String[] parameterNames = this.parameterNames;
+		@SuppressWarnings("NullAway") // Overridden method does not define nullness
+		public @Nullable String @Nullable [] getParameterNames() {
+			@Nullable String[] parameterNames = this.parameterNames;
 			if (parameterNames == null) {
 				parameterNames = parameterNameDiscoverer.getParameterNames(getMethod());
 				this.parameterNames = parameterNames;

Diff for: spring-aop/src/main/java/org/springframework/aop/aspectj/annotation/ReflectiveAspectJAdvisorFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -302,7 +302,7 @@ private List<Method> getAdvisorMethods(Class<?> aspectClass) {
 		// Now to configure the advice...
 		springAdvice.setAspectName(aspectName);
 		springAdvice.setDeclarationOrder(declarationOrder);
-		String[] argNames = this.parameterNameDiscoverer.getParameterNames(candidateAdviceMethod);
+		@Nullable String[] argNames = this.parameterNameDiscoverer.getParameterNames(candidateAdviceMethod);
 		if (argNames != null) {
 			springAdvice.setArgumentNamesFromStringArray(argNames);
 		}

Diff for: spring-aop/src/main/java/org/springframework/aop/framework/CglibAopProxy.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -704,7 +704,7 @@ public DynamicAdvisedInterceptor(AdvisedSupport advised) {
 					// Note that the final invoker must be an InvokerInterceptor, so we know
 					// it does nothing but a reflective operation on the target, and no hot
 					// swapping or fancy proxying.
-					Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);
+					@Nullable Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);
 					retVal = AopUtils.invokeJoinpointUsingReflection(target, method, argsToUse);
 				}
 				else {

Diff for: spring-aop/src/main/java/org/springframework/aop/framework/JdkDynamicAopProxy.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -211,7 +211,7 @@ else if (!this.advised.opaque && method.getDeclaringClass().isInterface() &&
 				// We can skip creating a MethodInvocation: just invoke the target directly
 				// Note that the final invoker must be an InvokerInterceptor so we know it does
 				// nothing but a reflective operation on the target, and no hot swapping or fancy proxying.
-				Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);
+				@Nullable Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);
 				retVal = AopUtils.invokeJoinpointUsingReflection(target, method, argsToUse);
 			}
 			else {

Diff for: spring-aop/src/main/java/org/springframework/aop/framework/ReflectiveMethodInvocation.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -201,7 +201,7 @@ public void setArguments(@Nullable Object... arguments) {
 	 */
 	@Override
 	public MethodInvocation invocableClone() {
-		Object[] cloneArguments = this.arguments;
+		@Nullable Object[] cloneArguments = this.arguments;
 		if (this.arguments.length > 0) {
 			// Build an independent copy of the arguments array.
 			cloneArguments = this.arguments.clone();

Diff for: spring-aop/src/main/java/org/springframework/aop/interceptor/AsyncExecutionAspectSupport.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2024 the original author or authors.
+ * Copyright 2002-2025 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.
@@ -116,8 +116,8 @@ public AsyncExecutionAspectSupport(@Nullable Executor defaultExecutor, AsyncUnca
 	 * applying the corresponding default if a supplier is not resolvable.
 	 * @since 5.1
 	 */
-	public void configure(@Nullable Supplier<Executor> defaultExecutor,
-			@Nullable Supplier<AsyncUncaughtExceptionHandler> exceptionHandler) {
+	public void configure(@Nullable Supplier<? extends @Nullable Executor> defaultExecutor,
+			@Nullable Supplier<? extends @Nullable AsyncUncaughtExceptionHandler> exceptionHandler) {
 
 		this.defaultExecutor = new SingletonSupplier<>(defaultExecutor, () -> getDefaultExecutor(this.beanFactory));
 		this.exceptionHandler = new SingletonSupplier<>(exceptionHandler, SimpleAsyncUncaughtExceptionHandler::new);