Refine null-safety in the spring-aop module

Closes gh-34154

Author: sdeleuze

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

@@ -545,14 +545,13 @@ private void configurePointcutParameters(String[] argumentNames, int argumentInd
 	 * @param ex the exception thrown by the method execution (may be null)
 	 * @return the empty array if there are no arguments
 	 */
-	@SuppressWarnings("NullAway")
-	protected Object[] argBinding(JoinPoint jp, @Nullable JoinPointMatch jpMatch,
+	protected @Nullable Object[] argBinding(JoinPoint jp, @Nullable JoinPointMatch jpMatch,
 			@Nullable Object returnValue, @Nullable Throwable ex) {
 
 		calculateArgumentBindings();
 
 		// AMC start
-		Object[] adviceInvocationArgs = new Object[this.parameterTypes.length];
+		@Nullable Object[] adviceInvocationArgs = new Object[this.parameterTypes.length];
 		int numBound = 0;
 
 		if (this.joinPointArgumentIndex != -1) {
@@ -571,19 +570,22 @@ else if (this.joinPointStaticPartArgumentIndex != -1) {
 				for (PointcutParameter parameter : parameterBindings) {
 					String name = parameter.getName();
 					Integer index = this.argumentBindings.get(name);
+					Assert.notNull(index, "Index must not be null");
 					adviceInvocationArgs[index] = parameter.getBinding();
 					numBound++;
 				}
 			}
 			// binding from returning clause
 			if (this.returningName != null) {
 				Integer index = this.argumentBindings.get(this.returningName);
+				Assert.notNull(index, "Index must not be null");
 				adviceInvocationArgs[index] = returnValue;
 				numBound++;
 			}
 			// binding from thrown exception
 			if (this.throwingName != null) {
 				Integer index = this.argumentBindings.get(this.throwingName);
+				Assert.notNull(index, "Index must not be null");
 				adviceInvocationArgs[index] = ex;
 				numBound++;
 			}

spring-aop/src/main/java/org/springframework/aop/aspectj/annotation/BeanFactoryAspectJAdvisorsBuilder.java

@@ -84,7 +84,6 @@ public BeanFactoryAspectJAdvisorsBuilder(ListableBeanFactory beanFactory, Aspect
 	 * @return the list of {@link org.springframework.aop.Advisor} beans
 	 * @see #isEligibleBean
 	 */
-	@SuppressWarnings("NullAway")
 	public List<Advisor> buildAspectJAdvisors() {
 		List<String> aspectNames = this.aspectBeanNames;
 
@@ -158,6 +157,7 @@ public List<Advisor> buildAspectJAdvisors() {
 			}
 			else {
 				MetadataAwareAspectInstanceFactory factory = this.aspectFactoryCache.get(aspectName);
+				Assert.notNull(factory, "Factory must not be null");
 				advisors.addAll(this.advisorFactory.getAdvisors(factory));
 			}
 		}

spring-aop/src/main/java/org/springframework/aop/aspectj/annotation/InstantiationModelAwarePointcutAdvisorImpl.java

@@ -75,9 +75,11 @@ final class InstantiationModelAwarePointcutAdvisorImpl
 
 	private @Nullable Advice instantiatedAdvice;
 
-	private @Nullable Boolean isBeforeAdvice;
+	@SuppressWarnings("NullAway.Init")
+	private Boolean isBeforeAdvice;
 
-	private @Nullable Boolean isAfterAdvice;
+	@SuppressWarnings("NullAway.Init")
+	private Boolean isAfterAdvice;
 
 
 	public InstantiationModelAwarePointcutAdvisorImpl(AspectJExpressionPointcut declaredPointcut,
@@ -192,7 +194,6 @@ public int getDeclarationOrder() {
 	}
 
 	@Override
-	@SuppressWarnings("NullAway")
 	public boolean isBeforeAdvice() {
 		if (this.isBeforeAdvice == null) {
 			determineAdviceType();
@@ -201,7 +202,6 @@ public boolean isBeforeAdvice() {
 	}
 
 	@Override
-	@SuppressWarnings("NullAway")
 	public boolean isAfterAdvice() {
 		if (this.isAfterAdvice == null) {
 			determineAdviceType();

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

@@ -304,7 +304,7 @@ else if (void.class == returnType || "kotlin.Unit".equals(returnType.getName()))
 	 * @param method the method that was invoked
 	 * @param params the parameters used to invoke the method
 	 */
-	protected void handleError(Throwable ex, Method method, Object... params) throws Exception {
+	protected void handleError(Throwable ex, Method method, @Nullable Object... params) throws Exception {
 		if (Future.class.isAssignableFrom(method.getReturnType())) {
 			ReflectionUtils.rethrowException(ex);
 		}

spring-aop/src/main/java/org/springframework/aop/interceptor/AsyncExecutionInterceptor.java

@@ -97,7 +97,6 @@ public AsyncExecutionInterceptor(@Nullable Executor defaultExecutor, AsyncUncaug
 	 * otherwise.
 	 */
 	@Override
-	@SuppressWarnings("NullAway")
 	public @Nullable Object invoke(final MethodInvocation invocation) throws Throwable {
 		Class<?> targetClass = (invocation.getThis() != null ? AopUtils.getTargetClass(invocation.getThis()) : null);
 		final Method userMethod = BridgeMethodResolver.getMostSpecificMethod(invocation.getMethod(), targetClass);
@@ -116,7 +115,8 @@ public AsyncExecutionInterceptor(@Nullable Executor defaultExecutor, AsyncUncaug
 				}
 			}
 			catch (ExecutionException ex) {
-				handleError(ex.getCause(), userMethod, invocation.getArguments());
+				Throwable cause = ex.getCause();
+				handleError(cause == null ? ex : cause, userMethod, invocation.getArguments());
 			}
 			catch (Throwable ex) {
 				handleError(ex, userMethod, invocation.getArguments());

spring-aop/src/main/java/org/springframework/aop/interceptor/AsyncUncaughtExceptionHandler.java

@@ -18,6 +18,8 @@
 
 import java.lang.reflect.Method;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * A strategy for handling uncaught exceptions thrown from asynchronous methods.
  *
@@ -38,6 +40,6 @@ public interface AsyncUncaughtExceptionHandler {
 	 * @param method the asynchronous method
 	 * @param params the parameters used to invoke the method
 	 */
-	void handleUncaughtException(Throwable ex, Method method, Object... params);
+	void handleUncaughtException(Throwable ex, Method method, @Nullable Object... params);
 
 }

spring-aop/src/main/java/org/springframework/aop/interceptor/SimpleAsyncUncaughtExceptionHandler.java

@@ -20,6 +20,7 @@
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 /**
  * A default {@link AsyncUncaughtExceptionHandler} that simply logs the exception.
@@ -34,7 +35,8 @@ public class SimpleAsyncUncaughtExceptionHandler implements AsyncUncaughtExcepti
 
 
 	@Override
-	public void handleUncaughtException(Throwable ex, Method method, Object... params) {
+	@SuppressWarnings("NullAway") // https://github.com/uber/NullAway/issues/1113
+	public void handleUncaughtException(Throwable ex, Method method, @Nullable Object... params) {
 		if (logger.isErrorEnabled()) {
 			logger.error("Unexpected exception occurred invoking async method: " + method, ex);
 		}

spring-aop/src/main/java/org/springframework/aop/scope/ScopedProxyBeanRegistrationAotProcessor.java

@@ -53,7 +53,7 @@ class ScopedProxyBeanRegistrationAotProcessor implements BeanRegistrationAotProc
 
 
 	@Override
-	@SuppressWarnings("NullAway")
+	@SuppressWarnings("NullAway") // Lambda
 	public @Nullable BeanRegistrationAotContribution processAheadOfTime(RegisteredBean registeredBean) {
 		Class<?> beanClass = registeredBean.getBeanClass();
 		if (beanClass.equals(ScopedProxyFactoryBean.class)) {

spring-aop/src/main/java/org/springframework/aop/support/annotation/AnnotationMatchingPointcut.java

@@ -88,7 +88,7 @@ public AnnotationMatchingPointcut(@Nullable Class<? extends Annotation> classAnn
 	 * @see AnnotationClassFilter#AnnotationClassFilter(Class, boolean)
 	 * @see AnnotationMethodMatcher#AnnotationMethodMatcher(Class, boolean)
 	 */
-	@SuppressWarnings("NullAway")
+	@SuppressWarnings("NullAway") // Dataflow analysis limitation
 	public AnnotationMatchingPointcut(@Nullable Class<? extends Annotation> classAnnotationType,
 			@Nullable Class<? extends Annotation> methodAnnotationType, boolean checkInherited) {
 

spring-aop/src/main/java/org/springframework/aop/target/dynamic/AbstractRefreshableTargetSource.java

@@ -42,7 +42,8 @@ public abstract class AbstractRefreshableTargetSource implements TargetSource, R
 	/** Logger available to subclasses. */
 	protected final Log logger = LogFactory.getLog(getClass());
 
-	protected @Nullable Object targetObject;
+	@SuppressWarnings("NullAway.Init")
+	protected Object targetObject;
 
 	private long refreshCheckDelay = -1;
 
@@ -65,7 +66,6 @@ public void setRefreshCheckDelay(long refreshCheckDelay) {
 
 
 	@Override
-	@SuppressWarnings("NullAway")
 	public synchronized Class<?> getTargetClass() {
 		if (this.targetObject == null) {
 			refresh();