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);

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

@@ -97,6 +97,7 @@ class ConfigBeanDefinitionParser implements BeanDefinitionParser {
 
 
 	@Override
+	@Nullable
 	public BeanDefinition parse(Element element, ParserContext parserContext) {
 		CompositeComponentDefinition compositeDef =
 				new CompositeComponentDefinition(element.getTagName(), parserContext.extractSource(element));

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

@@ -84,6 +84,7 @@ public void setBeanFactory(BeanFactory beanFactory) {
 
 
 	@Override
+	@Nullable
 	public Method getObject() throws Exception {
 		return this.method;
 	}

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

@@ -18,6 +18,7 @@
 
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.parsing.AbstractComponentDefinition;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -62,6 +63,7 @@ public BeanDefinition[] getBeanDefinitions() {
 	}
 
 	@Override
+	@Nullable
 	public Object getSource() {
 		return this.pointcutDefinition.getSource();
 	}

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

@@ -69,6 +69,7 @@ public Object getAspectInstance() {
 	}
 
 	@Override
+	@Nullable
 	public ClassLoader getAspectClassLoader() {
 		if (this.beanFactory instanceof ConfigurableBeanFactory) {
 			return ((ConfigurableBeanFactory) this.beanFactory).getBeanClassLoader();

spring-aop/src/main/java/org/springframework/aop/framework/AbstractSingletonProxyFactoryBean.java

@@ -221,6 +221,7 @@ public Object getObject() {
 	}
 
 	@Override
+	@Nullable
 	public Class<?> getObjectType() {
 		if (this.proxy != null) {
 			return this.proxy.getClass();

spring-aop/src/main/java/org/springframework/aop/framework/ProxyFactoryBean.java

@@ -247,6 +247,7 @@ public void setBeanFactory(BeanFactory beanFactory) {
 	 * @return a fresh AOP proxy reflecting the current state of this factory
 	 */
 	@Override
+	@Nullable
 	public Object getObject() throws BeansException {
 		initializeAdvisorChain();
 		if (isSingleton()) {

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

@@ -262,6 +262,7 @@ public void setUserAttribute(String key, @Nullable Object value) {
 	}
 
 	@Override
+	@Nullable
 	public Object getUserAttribute(String key) {
 		return (this.userAttributes != null ? this.userAttributes.get(key) : null);
 	}

spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/AbstractAutoProxyCreator.java

@@ -218,6 +218,7 @@ protected BeanFactory getBeanFactory() {
 
 
 	@Override
+	@Nullable
 	public Class<?> predictBeanType(Class<?> beanClass, String beanName) {
 		if (this.proxyTypes.isEmpty()) {
 			return null;
@@ -227,6 +228,7 @@ public Class<?> predictBeanType(Class<?> beanClass, String beanName) {
 	}
 
 	@Override
+	@Nullable
 	public Constructor<?>[] determineCandidateConstructors(Class<?> beanClass, String beanName) throws BeansException {
 		return null;
 	}

spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/target/AbstractBeanFactoryBasedTargetSourceCreator.java

@@ -89,6 +89,7 @@ protected final BeanFactory getBeanFactory() {
 	//---------------------------------------------------------------------
 
 	@Override
+	@Nullable
 	public final TargetSource getTargetSource(Class<?> beanClass, String beanName) {
 		AbstractBeanFactoryBasedTargetSource targetSource =
 				createBeanFactoryBasedTargetSource(beanClass, beanName);

spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/target/LazyInitTargetSourceCreator.java

@@ -20,6 +20,7 @@
 import org.springframework.aop.target.LazyInitTargetSource;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
+import org.springframework.lang.Nullable;
 
 /**
  * TargetSourceCreator that enforces a LazyInitTargetSource for each bean
@@ -59,6 +60,7 @@ protected boolean isPrototypeBased() {
 	}
 
 	@Override
+	@Nullable
 	protected AbstractBeanFactoryBasedTargetSource createBeanFactoryBasedTargetSource(
 			Class<?> beanClass, String beanName) {
 

spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/target/QuickTargetSourceCreator.java

@@ -20,6 +20,7 @@
 import org.springframework.aop.target.CommonsPool2TargetSource;
 import org.springframework.aop.target.PrototypeTargetSource;
 import org.springframework.aop.target.ThreadLocalTargetSource;
+import org.springframework.lang.Nullable;
 
 /**
  * Convenient TargetSourceCreator using bean name prefixes to create one of three
@@ -41,6 +42,7 @@ public class QuickTargetSourceCreator extends AbstractBeanFactoryBasedTargetSour
 	public static final String PREFIX_PROTOTYPE = "!";
 
 	@Override
+	@Nullable
 	protected final AbstractBeanFactoryBasedTargetSource createBeanFactoryBasedTargetSource(
 			Class<?> beanClass, String beanName) {
 

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

@@ -138,6 +138,7 @@ public Object invoke(final MethodInvocation invocation) throws Throwable {
 	 * @see #determineAsyncExecutor(Method)
 	 */
 	@Override
+	@Nullable
 	protected String getExecutorQualifier(Method method) {
 		return null;
 	}
@@ -151,6 +152,7 @@ protected String getExecutorQualifier(Method method) {
 	 * @see #DEFAULT_TASK_EXECUTOR_BEAN_NAME
 	 */
 	@Override
+	@Nullable
 	protected Executor getDefaultExecutor(@Nullable BeanFactory beanFactory) {
 		Executor defaultExecutor = super.getDefaultExecutor(beanFactory);
 		return (defaultExecutor != null ? defaultExecutor : new SimpleAsyncTaskExecutor());

spring-aop/src/main/java/org/springframework/aop/target/AbstractLazyCreationTargetSource.java

@@ -20,6 +20,7 @@
 import org.apache.commons.logging.LogFactory;
 
 import org.springframework.aop.TargetSource;
+import org.springframework.lang.Nullable;
 
 /**
  * {@link org.springframework.aop.TargetSource} implementation that will
@@ -65,6 +66,7 @@ public synchronized boolean isInitialized() {
 	 * @see #isInitialized()
 	 */
 	@Override
+	@Nullable
 	public synchronized Class<?> getTargetClass() {
 		return (this.lazyTarget != null ? this.lazyTarget.getClass() : null);
 	}

spring-aop/src/main/java/org/springframework/aop/target/AbstractPoolingTargetSource.java

@@ -22,6 +22,7 @@
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanInitializationException;
 import org.springframework.beans.factory.DisposableBean;
+import org.springframework.lang.Nullable;
 
 /**
  * Abstract base class for pooling {@link org.springframework.aop.TargetSource}
@@ -100,6 +101,7 @@ public final void setBeanFactory(BeanFactory beanFactory) throws BeansException
 	 * APIs, so we're forgiving with our exception signature
 	 */
 	@Override
+	@Nullable
 	public abstract Object getTarget() throws Exception;
 
 	/**

spring-aop/src/main/java/org/springframework/aop/target/CommonsPool2TargetSource.java

@@ -23,6 +23,8 @@
 import org.apache.commons.pool2.impl.GenericObjectPool;
 import org.apache.commons.pool2.impl.GenericObjectPoolConfig;
 
+import org.springframework.lang.Nullable;
+
 /**
  * {@link org.springframework.aop.TargetSource} implementation that holds
  * objects in a configurable Apache Commons2 Pool.
@@ -78,6 +80,7 @@ public class CommonsPool2TargetSource extends AbstractPoolingTargetSource implem
 	/**
 	 * The Apache Commons {@code ObjectPool} used to pool target objects
 	 */
+	@Nullable
 	private ObjectPool pool;
 
 

spring-aop/src/main/java/org/springframework/aop/target/EmptyTargetSource.java

@@ -92,6 +92,7 @@ private EmptyTargetSource(@Nullable Class<?> targetClass, boolean isStatic) {
 	 * Always returns the specified target Class, or {@code null} if none.
 	 */
 	@Override
+	@Nullable
 	public Class<?> getTargetClass() {
 		return this.targetClass;
 	}
@@ -108,6 +109,7 @@ public boolean isStatic() {
 	 * Always returns {@code null}.
 	 */
 	@Override
+	@Nullable
 	public Object getTarget() {
 		return null;
 	}

spring-aop/src/main/java/org/springframework/aop/target/LazyInitTargetSource.java

@@ -17,6 +17,7 @@
 package org.springframework.aop.target;
 
 import org.springframework.beans.BeansException;
+import org.springframework.lang.Nullable;
 
 /**
  * {@link org.springframework.aop.TargetSource} that lazily accesses a
@@ -59,10 +60,12 @@
 @SuppressWarnings("serial")
 public class LazyInitTargetSource extends AbstractBeanFactoryBasedTargetSource {
 
+	@Nullable
 	private Object target;
 
 
 	@Override
+	@Nullable
 	public synchronized Object getTarget() throws BeansException {
 		if (this.target == null) {
 			this.target = getBeanFactory().getBean(getTargetBeanName());

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

@@ -20,6 +20,7 @@
 import org.apache.commons.logging.LogFactory;
 
 import org.springframework.aop.TargetSource;
+import org.springframework.lang.Nullable;
 
 /**
  * Abstract {@link org.springframework.aop.TargetSource} implementation that
@@ -41,6 +42,7 @@ public abstract class AbstractRefreshableTargetSource implements TargetSource, R
 	/** Logger available to subclasses */
 	protected final Log logger = LogFactory.getLog(getClass());
 
+	@Nullable
 	protected Object targetObject;
 
 	private long refreshCheckDelay = -1;
@@ -80,6 +82,7 @@ public boolean isStatic() {
 	}
 
 	@Override
+	@Nullable
 	public final synchronized Object getTarget() {
 		if ((refreshCheckDelayElapsed() && requiresRefresh()) || this.targetObject == null) {
 			refresh();