Fix overridden methods nullability

Issue: SPR-15869

Author: sdeleuze

spring-aop/src/main/java/org/springframework/aop/TargetSource.java

@@ -42,6 +42,7 @@ public interface TargetSource extends TargetClassAware {
 	 * @return the type of targets returned by this {@link TargetSource}
 	 */
 	@Override
+	@Nullable
 	Class<?> getTargetClass();
 
 	/**

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

@@ -222,6 +222,7 @@ public void setThrowingName(@Nullable String throwingName) {
 	 * @return the parameter names
 	 */
 	@Override
+	@Nullable
 	public String[] getParameterNames(Method method) {
 		this.argumentTypes = method.getParameterTypes();
 		this.numberOfRemainingUnboundArguments = this.argumentTypes.length;
@@ -310,6 +311,7 @@ public String[] getParameterNames(Method method) {
 	 * {@link #setRaiseExceptions(boolean) raiseExceptions} has been set to {@code true}
 	 */
 	@Override
+	@Nullable
 	public String[] getParameterNames(Constructor<?> ctor) {
 		if (this.raiseExceptions) {
 			throw new UnsupportedOperationException("An advice method can never be a constructor");

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

@@ -20,6 +20,7 @@
 
 import org.springframework.aop.framework.AopConfigException;
 import org.springframework.core.Ordered;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ReflectionUtils;
 
@@ -76,6 +77,7 @@ public final Object getAspectInstance() {
 	}
 
 	@Override
+	@Nullable
 	public ClassLoader getAspectClassLoader() {
 		return this.aspectClass.getClassLoader();
 	}

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

@@ -19,6 +19,7 @@
 import java.io.Serializable;
 
 import org.springframework.core.Ordered;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -53,6 +54,7 @@ public final Object getAspectInstance() {
 	}
 
 	@Override
+	@Nullable
 	public ClassLoader getAspectClassLoader() {
 		return this.aspectInstance.getClass().getClassLoader();
 	}

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

@@ -261,6 +261,7 @@ public String toString() {
 	private static class AspectJAnnotationParameterNameDiscoverer implements ParameterNameDiscoverer {
 
 		@Override
+		@Nullable
 		public String[] getParameterNames(Method method) {
 			if (method.getParameterCount() == 0) {
 				return new String[0];
@@ -283,6 +284,7 @@ public String[] getParameterNames(Method method) {
 		}
 
 		@Override
+		@Nullable
 		public String[] getParameterNames(Constructor<?> ctor) {
 			throw new UnsupportedOperationException("Spring AOP cannot handle constructor advice");
 		}

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

@@ -91,6 +91,7 @@ public Object getAspectInstance() {
 	}
 
 	@Override
+	@Nullable
 	public ClassLoader getAspectClassLoader() {
 		return (this.beanFactory instanceof ConfigurableBeanFactory ?
 				((ConfigurableBeanFactory) this.beanFactory).getBeanClassLoader() :
@@ -103,6 +104,7 @@ public AspectMetadata getAspectMetadata() {
 	}
 
 	@Override
+	@Nullable
 	public Object getAspectCreationMutex() {
 		if (this.beanFactory.isSingleton(this.name)) {
 			// Rely on singleton semantics provided by the factory -> no local lock.

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

@@ -74,6 +74,7 @@ public boolean isMaterialized() {
 	}
 
 	@Override
+	@Nullable
 	public ClassLoader getAspectClassLoader() {
 		return this.maaif.getAspectClassLoader();
 	}
@@ -84,6 +85,7 @@ public AspectMetadata getAspectMetadata() {
 	}
 
 	@Override
+	@Nullable
 	public Object getAspectCreationMutex() {
 		return this.maaif.getAspectCreationMutex();
 	}

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

@@ -184,6 +184,7 @@ private Advisor getDeclareParentsAdvisor(Field introductionField) {
 
 
 	@Override
+	@Nullable
 	public Advisor getAdvisor(Method candidateAdviceMethod, MetadataAwareAspectInstanceFactory aspectInstanceFactory,
 			int declarationOrderInAspect, String aspectName) {
 
@@ -218,6 +219,7 @@ private AspectJExpressionPointcut getPointcut(Method candidateAdviceMethod, Clas
 
 
 	@Override
+	@Nullable
 	public Advice getAdvice(Method candidateAdviceMethod, AspectJExpressionPointcut expressionPointcut,
 			MetadataAwareAspectInstanceFactory aspectInstanceFactory, int declarationOrder, String aspectName) {
 

spring-aop/src/main/java/org/springframework/aop/config/AdvisorComponentDefinition.java

@@ -110,6 +110,7 @@ public BeanReference[] getBeanReferences() {
 	}
 
 	@Override
+	@Nullable
 	public Object getSource() {
 		return this.advisorDefinition.getSource();
 	}

spring-aop/src/main/java/org/springframework/aop/config/AspectJAutoProxyBeanDefinitionParser.java

@@ -25,6 +25,7 @@
 import org.springframework.beans.factory.support.ManagedList;
 import org.springframework.beans.factory.xml.BeanDefinitionParser;
 import org.springframework.beans.factory.xml.ParserContext;
+import org.springframework.lang.Nullable;
 
 /**
  * {@link BeanDefinitionParser} for the {@code aspectj-autoproxy} tag,
@@ -38,6 +39,7 @@
 class AspectJAutoProxyBeanDefinitionParser implements BeanDefinitionParser {
 
 	@Override
+	@Nullable
 	public BeanDefinition parse(Element element, ParserContext parserContext) {
 		AopNamespaceUtils.registerAspectJAnnotationAutoProxyCreatorIfNecessary(parserContext, element);
 		extendBeanDefinition(element, parserContext);