Consistent use of @Nullable across the codebase (even for internals)

Beyond just formally declaring the current behavior, this revision actually enforces non-null behavior in selected signatures now, not tolerating null values anymore when not explicitly documented. It also changes some utility methods with historic null-in/null-out tolerance towards enforced non-null return values, making them a proper citizen in non-null assignments.

Some issues are left as to-do: in particular a thorough revision of spring-test, and a few tests with unclear failures (ignored as "TODO: NULLABLE") to be sorted out in a follow-up commit.

Issue: SPR-15540

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.

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

@@ -1,5 +1,5 @@
 /*<
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -31,14 +31,14 @@ import org.springframework.lang.Nullable;
  * {@code TargetSources} directly: this is an AOP framework interface.
  *
  * @author Rod Johnson
+ * @author Juergen Hoeller
  */
 public interface TargetSource extends TargetClassAware {
 
 	/**
 	 * Return the type of targets returned by this {@link TargetSource}.
-	 * <p>Can return {@code null}, although certain usages of a
-	 * {@code TargetSource} might just work with a predetermined
-	 * target class.
+	 * <p>Can return {@code null}, although certain usages of a {@code TargetSource}
+	 * might just work with a predetermined target class.
 	 * @return the type of targets returned by this {@link TargetSource}
 	 */
 	@Override
@@ -46,9 +46,8 @@ public interface TargetSource extends TargetClassAware {
 
 	/**
 	 * Will all calls to {@link #getTarget()} return the same object?
-	 * <p>In that case, there will be no need to invoke
-	 * {@link #releaseTarget(Object)}, and the AOP framework can cache
-	 * the return value of {@link #getTarget()}.
+	 * <p>In that case, there will be no need to invoke {@link #releaseTarget(Object)},
+	 * and the AOP framework can cache the return value of {@link #getTarget()}.
 	 * @return {@code true} if the target is immutable
 	 * @see #getTarget
 	 */

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -208,6 +208,7 @@ public abstract class AbstractAspectJAdvice implements Advice, AspectJPrecedence
 	/**
 	 * Return the ClassLoader for aspect instances.
 	 */
+	@Nullable
 	public final ClassLoader getAspectClassLoader() {
 		return this.aspectInstanceFactory.getAspectClassLoader();
 	}
@@ -296,8 +297,8 @@ public abstract class AbstractAspectJAdvice implements Advice, AspectJPrecedence
 			}
 			catch (Throwable ex) {
 				throw new IllegalArgumentException("Returning name '" + name  +
-						"' is neither a valid argument name nor the fully-qualified name of a Java type on the classpath. " +
-						"Root cause: " + ex);
+						"' is neither a valid argument name nor the fully-qualified " +
+						"name of a Java type on the classpath. Root cause: " + ex);
 			}
 		}
 	}
@@ -306,6 +307,7 @@ public abstract class AbstractAspectJAdvice implements Advice, AspectJPrecedence
 		return this.discoveredReturningType;
 	}
 
+	@Nullable
 	protected Type getDiscoveredReturningGenericType() {
 		return this.discoveredReturningGenericType;
 	}
@@ -330,8 +332,8 @@ public abstract class AbstractAspectJAdvice implements Advice, AspectJPrecedence
 			}
 			catch (Throwable ex) {
 				throw new IllegalArgumentException("Throwing name '" + name  +
-						"' is neither a valid argument name nor the fully-qualified name of a Java type on the classpath. " +
-						"Root cause: " + ex);
+						"' is neither a valid argument name nor the fully-qualified " +
+						"name of a Java type on the classpath. Root cause: " + ex);
 			}
 		}
 	}
@@ -549,7 +551,9 @@ public abstract class AbstractAspectJAdvice implements Advice, AspectJPrecedence
 	 * @param ex the exception thrown by the method execution (may be null)
 	 * @return the empty array if there are no arguments
 	 */
-	protected Object[] argBinding(JoinPoint jp, JoinPointMatch jpMatch, @Nullable Object returnValue, @Nullable Throwable ex) {
+	protected Object[] argBinding(JoinPoint jp, @Nullable JoinPointMatch jpMatch,
+			@Nullable Object returnValue, @Nullable Throwable ex) {
+
 		calculateArgumentBindings();
 
 		// AMC start
@@ -608,13 +612,16 @@ public abstract class AbstractAspectJAdvice implements Advice, AspectJPrecedence
 	 * @return the invocation result
 	 * @throws Throwable in case of invocation failure
 	 */
-	protected Object invokeAdviceMethod(JoinPointMatch jpMatch, @Nullable Object returnValue, @Nullable Throwable ex) throws Throwable {
+	protected Object invokeAdviceMethod(
+			@Nullable JoinPointMatch jpMatch, @Nullable Object returnValue, @Nullable Throwable ex)
+			throws Throwable {
+
 		return invokeAdviceMethodWithGivenArgs(argBinding(getJoinPoint(), jpMatch, returnValue, ex));
 	}
 
 	// As above, but in this case we are given the join point.
-	protected Object invokeAdviceMethod(JoinPoint jp, JoinPointMatch jpMatch, Object returnValue, Throwable t)
-			throws Throwable {
+	protected Object invokeAdviceMethod(JoinPoint jp, @Nullable JoinPointMatch jpMatch,
+			@Nullable Object returnValue, @Nullable Throwable t) throws Throwable {
 
 		return invokeAdviceMethodWithGivenArgs(argBinding(jp, jpMatch, returnValue, t));
 	}
@@ -649,6 +656,7 @@ public abstract class AbstractAspectJAdvice implements Advice, AspectJPrecedence
 	/**
 	 * Get the current join point match at the join point we are being dispatched on.
 	 */
+	@Nullable
 	protected JoinPointMatch getJoinPointMatch() {
 		MethodInvocation mi = ExposeInvocationInterceptor.currentInvocation();
 		if (!(mi instanceof ProxyMethodInvocation)) {
@@ -663,8 +671,10 @@ public abstract class AbstractAspectJAdvice implements Advice, AspectJPrecedence
 	// 'last man wins' which is not what we want at all.
 	// Using the expression is guaranteed to be safe, since 2 identical expressions
 	// are guaranteed to bind in exactly the same way.
+	@Nullable
 	protected JoinPointMatch getJoinPointMatch(ProxyMethodInvocation pmi) {
-		return (JoinPointMatch) pmi.getUserAttribute(this.pointcut.getExpression());
+		String expression = this.pointcut.getExpression();
+		return (expression != null ? (JoinPointMatch) pmi.getUserAttribute(expression) : null);
 	}
 
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -17,6 +17,7 @@
 package org.springframework.aop.aspectj;
 
 import org.springframework.core.Ordered;
+import org.springframework.lang.Nullable;
 
 /**
  * Interface implemented to provide an instance of an AspectJ aspect.
@@ -40,8 +41,10 @@ public interface AspectInstanceFactory extends Ordered {
 
 	/**
 	 * Expose the aspect class loader that this factory uses.
-	 * @return the aspect class loader (never {@code null})
+	 * @return the aspect class loader (or {@code null} for the bootstrap loader)
+	 * @see org.springframework.util.ClassUtils#getDefaultClassLoader()
 	 */
+	@Nullable
 	ClassLoader getAspectClassLoader();
 
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -183,10 +183,11 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 	 * Create a new discoverer that attempts to discover parameter names
 	 * from the given pointcut expression.
 	 */
-	public AspectJAdviceParameterNameDiscoverer(String pointcutExpression) {
+	public AspectJAdviceParameterNameDiscoverer(@Nullable String pointcutExpression) {
 		this.pointcutExpression = pointcutExpression;
 	}
 
+
 	/**
 	 * Indicate whether {@link IllegalArgumentException} and {@link AmbiguousBindingException}
 	 * must be thrown as appropriate in the case of failing to deduce advice parameter names.
@@ -214,6 +215,7 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 		this.throwingName = throwingName;
 	}
 
+
 	/**
 	 * Deduce the parameter names for an advice method.
 	 * <p>See the {@link AspectJAdviceParameterNameDiscoverer class level javadoc}
@@ -475,8 +477,8 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 	 * If the token starts meets Java identifier conventions, it's in.
 	 */
 	@Nullable
-	private String maybeExtractVariableName(String candidateToken) {
-		if (candidateToken == null || candidateToken.equals("")) {
+	private String maybeExtractVariableName(@Nullable String candidateToken) {
+		if (!StringUtils.hasLength(candidateToken)) {
 			return null;
 		}
 		if (Character.isJavaIdentifierStart(candidateToken.charAt(0)) &&
@@ -498,7 +500,7 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 	 * Given an args pointcut body (could be {@code args} or {@code at_args}),
 	 * add any candidate variable names to the given list.
 	 */
-	private void maybeExtractVariableNamesFromArgs(String argsSpec, List<String> varNames) {
+	private void maybeExtractVariableNamesFromArgs(@Nullable String argsSpec, List<String> varNames) {
 		if (argsSpec == null) {
 			return;
 		}
@@ -781,7 +783,7 @@ public class AspectJAdviceParameterNameDiscoverer implements ParameterNameDiscov
 
 		private String text;
 
-		public PointcutBody(int tokens, String text) {
+		public PointcutBody(int tokens, @Nullable String text) {
 			this.numTokensConsumed = tokens;
 			this.text = text;
 		}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 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.

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -57,6 +57,7 @@ import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.annotation.BeanFactoryAnnotationUtils;
 import org.springframework.beans.factory.config.ConfigurableBeanFactory;
 import org.springframework.lang.Nullable;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
 import org.springframework.util.StringUtils;
@@ -196,6 +197,7 @@ public class AspectJExpressionPointcut extends AbstractExpressionPointcut
 	/**
 	 * Determine the ClassLoader to use for pointcut evaluation.
 	 */
+	@Nullable
 	private ClassLoader determinePointcutClassLoader() {
 		if (this.beanFactory instanceof ConfigurableBeanFactory) {
 			return ((ConfigurableBeanFactory) this.beanFactory).getBeanClassLoader();
@@ -209,21 +211,27 @@ public class AspectJExpressionPointcut extends AbstractExpressionPointcut
 	/**
 	 * Build the underlying AspectJ pointcut expression.
 	 */
-	private PointcutExpression buildPointcutExpression(ClassLoader classLoader) {
+	private PointcutExpression buildPointcutExpression(@Nullable ClassLoader classLoader) {
 		PointcutParser parser = initializePointcutParser(classLoader);
 		PointcutParameter[] pointcutParameters = new PointcutParameter[this.pointcutParameterNames.length];
 		for (int i = 0; i < pointcutParameters.length; i++) {
 			pointcutParameters[i] = parser.createPointcutParameter(
 					this.pointcutParameterNames[i], this.pointcutParameterTypes[i]);
 		}
-		return parser.parsePointcutExpression(replaceBooleanOperators(getExpression()),
+		return parser.parsePointcutExpression(replaceBooleanOperators(resolveExpression()),
 				this.pointcutDeclarationScope, pointcutParameters);
 	}
 
+	private String resolveExpression() {
+		String expression = getExpression();
+		Assert.state(expression != null, "No expression set");
+		return expression;
+	}
+
 	/**
 	 * Initialize the underlying AspectJ pointcut parser.
 	 */
-	private PointcutParser initializePointcutParser(ClassLoader classLoader) {
+	private PointcutParser initializePointcutParser(@Nullable ClassLoader classLoader) {
 		PointcutParser parser = PointcutParser
 				.getPointcutParserSupportingSpecifiedPrimitivesAndUsingSpecifiedClassLoaderForResolution(
 						SUPPORTED_PRIMITIVES, classLoader);
@@ -301,7 +309,8 @@ public class AspectJExpressionPointcut extends AbstractExpressionPointcut
 			// we say this is not a match as in Spring there will never be a different
 			// runtime subtype.
 			RuntimeTestWalker walker = getRuntimeTestWalker(shadowMatch);
-			return (!walker.testsSubtypeSensitiveVars() || walker.testTargetInstanceOfResidue(targetClass));
+			return (!walker.testsSubtypeSensitiveVars() ||
+					(targetClass != null && walker.testTargetInstanceOfResidue(targetClass)));
 		}
 	}
 
@@ -354,7 +363,7 @@ public class AspectJExpressionPointcut extends AbstractExpressionPointcut
 			 * type but not 'this' (as would be the case of JDK dynamic proxies).
 			 * <p>See SPR-2979 for the original bug.
 			 */
-			if (pmi != null) {  // there is a current invocation
+			if (pmi != null && thisObject != null) {  // there is a current invocation
 				RuntimeTestWalker originalMethodResidueTest = getRuntimeTestWalker(originalShadowMatch);
 				if (!originalMethodResidueTest.testThisInstanceOfResidue(thisObject.getClass())) {
 					return false;
@@ -375,6 +384,7 @@ public class AspectJExpressionPointcut extends AbstractExpressionPointcut
 		}
 	}
 
+	@Nullable
 	protected String getCurrentProxiedBeanName() {
 		return ProxyCreationContext.getCurrentProxiedBeanName();
 	}
@@ -411,7 +421,7 @@ public class AspectJExpressionPointcut extends AbstractExpressionPointcut
 		// 'last man wins' which is not what we want at all.
 		// Using the expression is guaranteed to be safe, since 2 identical expressions
 		// are guaranteed to bind in exactly the same way.
-		invocation.setUserAttribute(getExpression(), jpm);
+		invocation.setUserAttribute(resolveExpression(), jpm);
 	}
 
 	private ShadowMatch getShadowMatch(Method targetMethod, Method originalMethod) {
@@ -600,7 +610,7 @@ public class AspectJExpressionPointcut extends AbstractExpressionPointcut
 			return false;
 		}
 
-		private FuzzyBoolean contextMatch(Class<?> targetType) {
+		private FuzzyBoolean contextMatch(@Nullable Class<?> targetType) {
 			String advisedBeanName = getCurrentProxiedBeanName();
 			if (advisedBeanName == null) {  // no proxy creation in progress
 				// abstain; can't return YES, since that will make pointcut with negation fail

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -20,6 +20,7 @@ import org.springframework.aop.Pointcut;
 import org.springframework.aop.support.AbstractGenericPointcutAdvisor;
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanFactoryAware;
+import org.springframework.lang.Nullable;
 
 /**
  * Spring AOP Advisor that can be used for any AspectJ pointcut expression.
@@ -37,6 +38,7 @@ public class AspectJExpressionPointcutAdvisor extends AbstractGenericPointcutAdv
 		this.pointcut.setExpression(expression);
 	}
 
+	@Nullable
 	public String getExpression() {
 		return this.pointcut.getExpression();
 	}
@@ -45,6 +47,7 @@ public class AspectJExpressionPointcutAdvisor extends AbstractGenericPointcutAdv
 		this.pointcut.setLocation(location);
 	}
 
+	@Nullable
 	public String getLocation() {
 		return this.pointcut.getLocation();
 	}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -212,6 +212,7 @@ public abstract class AbstractAspectJAdvisorFactory implements AspectJAdvisorFac
 			throw new IllegalStateException("Unknown annotation type: " + annotation.toString());
 		}
 
+		@Nullable
 		private String resolveExpression(A annotation) throws Exception {
 			String expression = null;
 			for (String methodName : EXPRESSION_PROPERTIES) {

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -119,7 +119,9 @@ public class AspectJProxyFactory extends ProxyCreatorSupport {
 	 */
 	private void addAdvisorsFromAspectInstanceFactory(MetadataAwareAspectInstanceFactory instanceFactory) {
 		List<Advisor> advisors = this.aspectFactory.getAdvisors(instanceFactory);
-		advisors = AopUtils.findAdvisorsThatCanApply(advisors, getTargetClass());
+		Class<?> targetClass = getTargetClass();
+		Assert.state(targetClass != null, "Unresolvable target class");
+		advisors = AopUtils.findAdvisorsThatCanApply(advisors, targetClass);
 		AspectJProxyUtils.makeAdvisorChainAspectJCapableIfNecessary(advisors);
 		AnnotationAwareOrderComparator.sort(advisors);
 		addAdvisors(advisors);

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -22,6 +22,7 @@ import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.config.ConfigurableBeanFactory;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.OrderUtils;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
@@ -58,7 +59,7 @@ public class BeanFactoryAspectInstanceFactory implements MetadataAwareAspectInst
 	 * @param name name of the bean
 	 */
 	public BeanFactoryAspectInstanceFactory(BeanFactory beanFactory, String name) {
-		this(beanFactory, name, beanFactory.getType(name));
+		this(beanFactory, name, null);
 	}
 
 	/**
@@ -68,13 +69,19 @@ public class BeanFactoryAspectInstanceFactory implements MetadataAwareAspectInst
 	 * @param beanFactory BeanFactory to obtain instance(s) from
 	 * @param name the name of the bean
 	 * @param type the type that should be introspected by AspectJ
+	 * ({@code null} indicates resolution through {@link BeanFactory#getType} via the bean name)
 	 */
-	public BeanFactoryAspectInstanceFactory(BeanFactory beanFactory, String name, Class<?> type) {
+	public BeanFactoryAspectInstanceFactory(BeanFactory beanFactory, String name, @Nullable Class<?> type) {
 		Assert.notNull(beanFactory, "BeanFactory must not be null");
 		Assert.notNull(name, "Bean name must not be null");
 		this.beanFactory = beanFactory;
 		this.name = name;
-		this.aspectMetadata = new AspectMetadata(type, name);
+		Class<?> resolvedType = type;
+		if (type == null) {
+			resolvedType = beanFactory.getType(name);
+			Assert.notNull(resolvedType, "Unresolvable bean type - explicitly specify the aspect class");
+		}
+		this.aspectMetadata = new AspectMetadata(resolvedType, name);
 	}
 
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -45,6 +45,9 @@ import org.springframework.lang.Nullable;
 class InstantiationModelAwarePointcutAdvisorImpl
 		implements InstantiationModelAwarePointcutAdvisor, AspectJPrecedenceInformation, Serializable {
 
+	private static Advice EMPTY_ADVICE = new Advice() {};
+
+
 	private final AspectJExpressionPointcut declaredPointcut;
 
 	private final Class<?> declaringClass;
@@ -157,9 +160,10 @@ class InstantiationModelAwarePointcutAdvisorImpl
 	}
 
 
-	private Advice instantiateAdvice(AspectJExpressionPointcut pcut) {
-		return this.aspectJAdvisorFactory.getAdvice(this.aspectJAdviceMethod, pcut,
+	private Advice instantiateAdvice(AspectJExpressionPointcut pointcut) {
+		Advice advice = this.aspectJAdvisorFactory.getAdvice(this.aspectJAdviceMethod, pointcut,
 				this.aspectInstanceFactory, this.declarationOrder, this.aspectName);
+		return (advice != null ? advice : EMPTY_ADVICE);
 	}
 
 	public MetadataAwareAspectInstanceFactory getAspectInstanceFactory() {

spring-aop/src/main/java/org/springframework/aop/aspectj/autoproxy/AspectJPrecedenceComparator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -132,7 +132,9 @@ class AspectJPrecedenceComparator implements Comparator<Advisor> {
 
 	// pre-condition is that hasAspectName returned true
 	private String getAspectName(Advisor anAdvisor) {
-		return AspectJAopUtils.getAspectJPrecedenceInformationFor(anAdvisor).getAspectName();
+		AspectJPrecedenceInformation pi = AspectJAopUtils.getAspectJPrecedenceInformationFor(anAdvisor);
+		Assert.state(pi != null, "Unresolvable precedence information");
+		return pi.getAspectName();
 	}
 
 	private int getAspectDeclarationOrder(Advisor anAdvisor) {

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -30,6 +30,7 @@ import org.springframework.beans.factory.support.ManagedList;
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.beans.factory.xml.BeanDefinitionDecorator;
 import org.springframework.beans.factory.xml.ParserContext;
+import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.StringUtils;
 
@@ -105,8 +106,8 @@ public abstract class AbstractInterceptorDrivenBeanDefinitionDecorator implement
 
 	@SuppressWarnings("unchecked")
 	private void addInterceptorNameToList(String interceptorName, BeanDefinition beanDefinition) {
-		List<String> list = (List<String>)
-				beanDefinition.getPropertyValues().getPropertyValue("interceptorNames").getValue();
+		List<String> list = (List<String>) beanDefinition.getPropertyValues().get("interceptorNames");
+		Assert.state(list != null, "Missing 'interceptorNames' property");
 		list.add(interceptorName);
 	}
 
@@ -115,7 +116,9 @@ public abstract class AbstractInterceptorDrivenBeanDefinitionDecorator implement
 	}
 
 	protected String getInterceptorNameSuffix(BeanDefinition interceptorDefinition) {
-		return StringUtils.uncapitalize(ClassUtils.getShortName(interceptorDefinition.getBeanClassName()));
+		String beanClassName = interceptorDefinition.getBeanClassName();
+		return (StringUtils.hasLength(beanClassName) ?
+				StringUtils.uncapitalize(ClassUtils.getShortName(beanClassName)) : "");
 	}
 
 	/**

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -20,6 +20,7 @@ import org.springframework.beans.MutablePropertyValues;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.BeanReference;
 import org.springframework.beans.factory.parsing.AbstractComponentDefinition;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -50,7 +51,7 @@ public class AdvisorComponentDefinition extends AbstractComponentDefinition {
 	}
 
 	public AdvisorComponentDefinition(
-			String advisorBeanName, BeanDefinition advisorDefinition, BeanDefinition pointcutDefinition) {
+			String advisorBeanName, BeanDefinition advisorDefinition, @Nullable BeanDefinition pointcutDefinition) {
 
 		Assert.notNull(advisorBeanName, "'advisorBeanName' must not be null");
 		Assert.notNull(advisorDefinition, "'advisorDefinition' must not be null");
@@ -60,9 +61,10 @@ public class AdvisorComponentDefinition extends AbstractComponentDefinition {
 	}
 
 
-	private void unwrapDefinitions(BeanDefinition advisorDefinition, BeanDefinition pointcutDefinition) {
+	private void unwrapDefinitions(BeanDefinition advisorDefinition, @Nullable BeanDefinition pointcutDefinition) {
 		MutablePropertyValues pvs = advisorDefinition.getPropertyValues();
-		BeanReference adviceReference = (BeanReference) pvs.getPropertyValue("adviceBeanName").getValue();
+		BeanReference adviceReference = (BeanReference) pvs.get("adviceBeanName");
+		Assert.state(adviceReference != null, "Missing 'adviceBeanName' property");
 
 		if (pointcutDefinition != null) {
 			this.beanReferences = new BeanReference[] {adviceReference};
@@ -70,7 +72,8 @@ public class AdvisorComponentDefinition extends AbstractComponentDefinition {
 			this.description = buildDescription(adviceReference, pointcutDefinition);
 		}
 		else {
-			BeanReference pointcutReference = (BeanReference) pvs.getPropertyValue("pointcut").getValue();
+			BeanReference pointcutReference = (BeanReference) pvs.get("pointcut");
+			Assert.state(pointcutReference != null, "Missing 'pointcut' property");
 			this.beanReferences = new BeanReference[] {adviceReference, pointcutReference};
 			this.beanDefinitions = new BeanDefinition[] {advisorDefinition};
 			this.description = buildDescription(adviceReference, pointcutReference);
@@ -78,16 +81,15 @@ public class AdvisorComponentDefinition extends AbstractComponentDefinition {
 	}
 
 	private String buildDescription(BeanReference adviceReference, BeanDefinition pointcutDefinition) {
-		return new StringBuilder("Advisor <advice(ref)='").
-				append(adviceReference.getBeanName()).append("', pointcut(expression)=[").
-				append(pointcutDefinition.getPropertyValues().getPropertyValue("expression").getValue()).
-				append("]>").toString();
+		return "Advisor <advice(ref)='" +
+				adviceReference.getBeanName() + "', pointcut(expression)=[" +
+				pointcutDefinition.getPropertyValues().get("expression") + "]>";
 	}
 
 	private String buildDescription(BeanReference adviceReference, BeanReference pointcutReference) {
-		return new StringBuilder("Advisor <advice(ref)='").
-				append(adviceReference.getBeanName()).append("', pointcut(ref)='").
-				append(pointcutReference.getBeanName()).append("'>").toString();
+		return "Advisor <advice(ref)='" +
+				adviceReference.getBeanName() + "', pointcut(ref)='" +
+				pointcutReference.getBeanName() + "'>";
 	}
 
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -67,27 +67,39 @@ public abstract class AopConfigUtils {
 	}
 
 
+	@Nullable
 	public static BeanDefinition registerAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry) {
 		return registerAutoProxyCreatorIfNecessary(registry, null);
 	}
 
-	public static BeanDefinition registerAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry, Object source) {
+	@Nullable
+	public static BeanDefinition registerAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry,
+			@Nullable Object source) {
+
 		return registerOrEscalateApcAsRequired(InfrastructureAdvisorAutoProxyCreator.class, registry, source);
 	}
 
+	@Nullable
 	public static BeanDefinition registerAspectJAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry) {
 		return registerAspectJAutoProxyCreatorIfNecessary(registry, null);
 	}
 
-	public static BeanDefinition registerAspectJAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry, Object source) {
+	@Nullable
+	public static BeanDefinition registerAspectJAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry,
+			@Nullable Object source) {
+
 		return registerOrEscalateApcAsRequired(AspectJAwareAdvisorAutoProxyCreator.class, registry, source);
 	}
 
+	@Nullable
 	public static BeanDefinition registerAspectJAnnotationAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry) {
 		return registerAspectJAnnotationAutoProxyCreatorIfNecessary(registry, null);
 	}
 
-	public static BeanDefinition registerAspectJAnnotationAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry, Object source) {
+	@Nullable
+	public static BeanDefinition registerAspectJAnnotationAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry,
+			@Nullable Object source) {
+
 		return registerOrEscalateApcAsRequired(AnnotationAwareAspectJAutoProxyCreator.class, registry, source);
 	}
 
@@ -106,8 +118,11 @@ public abstract class AopConfigUtils {
 	}
 
 	@Nullable
-	private static BeanDefinition registerOrEscalateApcAsRequired(Class<?> cls, BeanDefinitionRegistry registry, Object source) {
+	private static BeanDefinition registerOrEscalateApcAsRequired(Class<?> cls, BeanDefinitionRegistry registry,
+			@Nullable Object source) {
+
 		Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
+
 		if (registry.containsBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME)) {
 			BeanDefinition apcDefinition = registry.getBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME);
 			if (!cls.getName().equals(apcDefinition.getBeanClassName())) {
@@ -119,6 +134,7 @@ public abstract class AopConfigUtils {
 			}
 			return null;
 		}
+
 		RootBeanDefinition beanDefinition = new RootBeanDefinition(cls);
 		beanDefinition.setSource(source);
 		beanDefinition.getPropertyValues().add("order", Ordered.HIGHEST_PRECEDENCE);
@@ -131,7 +147,7 @@ public abstract class AopConfigUtils {
 		return APC_PRIORITY_LIST.indexOf(clazz);
 	}
 
-	private static int findPriorityForClass(String className) {
+	private static int findPriorityForClass(@Nullable String className) {
 		for (int i = 0; i < APC_PRIORITY_LIST.size(); i++) {
 			Class<?> clazz = APC_PRIORITY_LIST.get(i);
 			if (clazz.getName().equals(className)) {

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -22,6 +22,7 @@ import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.parsing.BeanComponentDefinition;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.xml.ParserContext;
+import org.springframework.lang.Nullable;
 
 /**
  * Utility class for handling registration of auto-proxy creators used internally
@@ -79,7 +80,7 @@ public abstract class AopNamespaceUtils {
 		registerComponentIfNecessary(beanDefinition, parserContext);
 	}
 
-	private static void useClassProxyingIfNecessary(BeanDefinitionRegistry registry, Element sourceElement) {
+	private static void useClassProxyingIfNecessary(BeanDefinitionRegistry registry, @Nullable Element sourceElement) {
 		if (sourceElement != null) {
 			boolean proxyTargetClass = Boolean.valueOf(sourceElement.getAttribute(PROXY_TARGET_CLASS_ATTRIBUTE));
 			if (proxyTargetClass) {
@@ -92,7 +93,7 @@ public abstract class AopNamespaceUtils {
 		}
 	}
 
-	private static void registerComponentIfNecessary(BeanDefinition beanDefinition, ParserContext parserContext) {
+	private static void registerComponentIfNecessary(@Nullable BeanDefinition beanDefinition, ParserContext parserContext) {
 		if (beanDefinition != null) {
 			BeanComponentDefinition componentDefinition =
 					new BeanComponentDefinition(beanDefinition, AopConfigUtils.AUTO_PROXY_CREATOR_BEAN_NAME);

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2007 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -19,6 +19,7 @@ package org.springframework.aop.config;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.BeanReference;
 import org.springframework.beans.factory.parsing.CompositeComponentDefinition;
+import org.springframework.lang.Nullable;
 
 /**
  * {@link org.springframework.beans.factory.parsing.ComponentDefinition}
@@ -37,8 +38,8 @@ public class AspectComponentDefinition extends CompositeComponentDefinition {
 	private final BeanReference[] beanReferences;
 
 
-	public AspectComponentDefinition(
-			String aspectName, BeanDefinition[] beanDefinitions, BeanReference[] beanReferences, Object source) {
+	public AspectComponentDefinition(String aspectName, @Nullable BeanDefinition[] beanDefinitions,
+			@Nullable BeanReference[] beanReferences, @Nullable Object source) {
 
 		super(aspectName, source);
 		this.beanDefinitions = (beanDefinitions != null ? beanDefinitions : new BeanDefinition[0]);

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -124,7 +124,7 @@ public abstract class AbstractSingletonProxyFactoryBean extends ProxyConfig
 	}
 
 	@Override
-	public void setBeanClassLoader(@Nullable ClassLoader classLoader) {
+	public void setBeanClassLoader(ClassLoader classLoader) {
 		if (this.proxyClassLoader == null) {
 			this.proxyClassLoader = classLoader;
 		}
@@ -170,8 +170,10 @@ public abstract class AbstractSingletonProxyFactoryBean extends ProxyConfig
 		}
 		else if (!isProxyTargetClass()) {
 			// Rely on AOP infrastructure to tell us what interfaces to proxy.
-			proxyFactory.setInterfaces(
-					ClassUtils.getAllInterfacesForClass(targetSource.getTargetClass(), this.proxyClassLoader));
+			Class<?> targetClass = targetSource.getTargetClass();
+			if (targetClass != null) {
+				proxyFactory.setInterfaces(ClassUtils.getAllInterfacesForClass(targetClass, this.proxyClassLoader));
+			}
 		}
 
 		postProcessProxyFactory(proxyFactory);

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -38,6 +38,7 @@ import org.springframework.aop.support.DefaultIntroductionAdvisor;
 import org.springframework.aop.support.DefaultPointcutAdvisor;
 import org.springframework.aop.target.EmptyTargetSource;
 import org.springframework.aop.target.SingletonTargetSource;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.CollectionUtils;
@@ -137,7 +138,7 @@ public class AdvisedSupport extends ProxyConfig implements Advised {
 	}
 
 	@Override
-	public void setTargetSource(TargetSource targetSource) {
+	public void setTargetSource(@Nullable TargetSource targetSource) {
 		this.targetSource = (targetSource != null ? targetSource : EMPTY_TARGET_SOURCE);
 	}
 
@@ -446,7 +447,7 @@ public class AdvisedSupport extends ProxyConfig implements Advised {
 	 * @param advice the advice to check inclusion of
 	 * @return whether this advice instance is included
 	 */
-	public boolean adviceIncluded(Advice advice) {
+	public boolean adviceIncluded(@Nullable Advice advice) {
 		if (advice != null) {
 			for (Advisor advisor : this.advisors) {
 				if (advisor.getAdvice() == advice) {
@@ -462,7 +463,7 @@ public class AdvisedSupport extends ProxyConfig implements Advised {
 	 * @param adviceClass the advice class to check
 	 * @return the count of the interceptors of this class or subclasses
 	 */
-	public int countAdvicesOfType(Class<?> adviceClass) {
+	public int countAdvicesOfType(@Nullable Class<?> adviceClass) {
 		int count = 0;
 		if (adviceClass != null) {
 			for (Advisor advisor : this.advisors) {
@@ -482,7 +483,7 @@ public class AdvisedSupport extends ProxyConfig implements Advised {
 	 * @param targetClass the target class
 	 * @return List of MethodInterceptors (may also include InterceptorAndDynamicMethodMatchers)
 	 */
-	public List<Object> getInterceptorsAndDynamicInterceptionAdvice(Method method, Class<?> targetClass) {
+	public List<Object> getInterceptorsAndDynamicInterceptionAdvice(Method method, @Nullable Class<?> targetClass) {
 		MethodCacheKey cacheKey = new MethodCacheKey(method);
 		List<Object> cached = this.methodCache.get(cacheKey);
 		if (cached == null) {

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

@@ -134,7 +134,7 @@ class CglibAopProxy implements AopProxy, Serializable {
 	 * @param constructorArgs the constructor argument values
 	 * @param constructorArgTypes the constructor argument types
 	 */
-	public void setConstructorArguments(Object[] constructorArgs, Class<?>[] constructorArgTypes) {
+	public void setConstructorArguments(@Nullable Object[] constructorArgs, @Nullable Class<?>[] constructorArgTypes) {
 		if (constructorArgs == null || constructorArgTypes == null) {
 			throw new IllegalArgumentException("Both 'constructorArgs' and 'constructorArgTypes' need to be specified");
 		}
@@ -233,7 +233,7 @@ class CglibAopProxy implements AopProxy, Serializable {
 	 * Checks to see whether the supplied {@code Class} has already been validated and
 	 * validates it if not.
 	 */
-	private void validateClassIfNecessary(Class<?> proxySuperClass, ClassLoader proxyClassLoader) {
+	private void validateClassIfNecessary(Class<?> proxySuperClass, @Nullable ClassLoader proxyClassLoader) {
 		if (logger.isWarnEnabled()) {
 			synchronized (validatedClasses) {
 				if (!validatedClasses.containsKey(proxySuperClass)) {
@@ -249,7 +249,7 @@ class CglibAopProxy implements AopProxy, Serializable {
 	 * Checks for final methods on the given {@code Class}, as well as package-visible
 	 * methods across ClassLoaders, and writes warnings to the log for each one found.
 	 */
-	private void doValidateClass(Class<?> proxySuperClass, ClassLoader proxyClassLoader, Set<Class<?>> ifcs) {
+	private void doValidateClass(Class<?> proxySuperClass, @Nullable ClassLoader proxyClassLoader, Set<Class<?>> ifcs) {
 		if (proxySuperClass != Object.class) {
 			Method[] methods = proxySuperClass.getDeclaredMethods();
 			for (Method method : methods) {
@@ -374,7 +374,7 @@ class CglibAopProxy implements AopProxy, Serializable {
 	 * {@code proxy} and also verifies that {@code null} is not returned as a primitive.
 	 */
 	@Nullable
-	private static Object processReturnType(Object proxy, Object target, Method method, @Nullable Object retVal) {
+	private static Object processReturnType(Object proxy, @Nullable Object target, Method method, @Nullable Object retVal) {
 		// Massage return value if necessary
 		if (retVal != null && retVal == target &&
 				!RawTargetAccess.class.isAssignableFrom(method.getDeclaringClass())) {
@@ -409,11 +409,12 @@ class CglibAopProxy implements AopProxy, Serializable {
 
 		private final Object target;
 
-		public StaticUnadvisedInterceptor(Object target) {
+		public StaticUnadvisedInterceptor(@Nullable Object target) {
 			this.target = target;
 		}
 
 		@Override
+		@Nullable
 		public Object intercept(Object proxy, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
 			Object retVal = methodProxy.invoke(this.target, args);
 			return processReturnType(proxy, this.target, method, retVal);
@@ -429,11 +430,12 @@ class CglibAopProxy implements AopProxy, Serializable {
 
 		private final Object target;
 
-		public StaticUnadvisedExposedInterceptor(Object target) {
+		public StaticUnadvisedExposedInterceptor(@Nullable Object target) {
 			this.target = target;
 		}
 
 		@Override
+		@Nullable
 		public Object intercept(Object proxy, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
 			Object oldProxy = null;
 			try {
@@ -462,6 +464,7 @@ class CglibAopProxy implements AopProxy, Serializable {
 		}
 
 		@Override
+		@Nullable
 		public Object intercept(Object proxy, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
 			Object target = this.targetSource.getTarget();
 			try {
@@ -469,7 +472,9 @@ class CglibAopProxy implements AopProxy, Serializable {
 				return processReturnType(proxy, target, method, retVal);
 			}
 			finally {
-				this.targetSource.releaseTarget(target);
+				if (target != null) {
+					this.targetSource.releaseTarget(target);
+				}
 			}
 		}
 	}
@@ -487,6 +492,7 @@ class CglibAopProxy implements AopProxy, Serializable {
 		}
 
 		@Override
+		@Nullable
 		public Object intercept(Object proxy, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
 			Object oldProxy = null;
 			Object target = this.targetSource.getTarget();
@@ -497,7 +503,9 @@ class CglibAopProxy implements AopProxy, Serializable {
 			}
 			finally {
 				AopContext.setCurrentProxy(oldProxy);
-				this.targetSource.releaseTarget(target);
+				if (target != null) {
+					this.targetSource.releaseTarget(target);
+				}
 			}
 		}
 	}
@@ -512,7 +520,7 @@ class CglibAopProxy implements AopProxy, Serializable {
 
 		private Object target;
 
-		public StaticDispatcher(Object target) {
+		public StaticDispatcher(@Nullable Object target) {
 			this.target = target;
 		}
 
@@ -604,13 +612,16 @@ class CglibAopProxy implements AopProxy, Serializable {
 
 		private final Class<?> targetClass;
 
-		public FixedChainStaticTargetInterceptor(List<Object> adviceChain, Object target, Class<?> targetClass) {
+		public FixedChainStaticTargetInterceptor(
+				List<Object> adviceChain, @Nullable Object target, @Nullable Class<?> targetClass) {
+
 			this.adviceChain = adviceChain;
 			this.target = target;
 			this.targetClass = targetClass;
 		}
 
 		@Override
+		@Nullable
 		public Object intercept(Object proxy, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
 			MethodInvocation invocation = new CglibMethodInvocation(proxy, this.target, method, args,
 					this.targetClass, this.adviceChain, methodProxy);
@@ -635,6 +646,7 @@ class CglibAopProxy implements AopProxy, Serializable {
 		}
 
 		@Override
+		@Nullable
 		public Object intercept(Object proxy, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
 			Object oldProxy = null;
 			boolean setProxyContext = false;
@@ -697,6 +709,7 @@ class CglibAopProxy implements AopProxy, Serializable {
 			return this.advised.hashCode();
 		}
 
+		@Nullable
 		protected Object getTarget() throws Exception {
 			return this.advised.getTargetSource().getTarget();
 		}
@@ -716,8 +729,9 @@ class CglibAopProxy implements AopProxy, Serializable {
 
 		private final boolean publicMethod;
 
-		public CglibMethodInvocation(Object proxy, Object target, Method method, Object[] arguments,
-				Class<?> targetClass, List<Object> interceptorsAndDynamicMethodMatchers, MethodProxy methodProxy) {
+		public CglibMethodInvocation(Object proxy, @Nullable Object target, Method method,
+				Object[] arguments, @Nullable Class<?> targetClass,
+				List<Object> interceptorsAndDynamicMethodMatchers, MethodProxy methodProxy) {
 
 			super(proxy, target, method, arguments, targetClass, interceptorsAndDynamicMethodMatchers);
 			this.methodProxy = methodProxy;
@@ -751,7 +765,9 @@ class CglibAopProxy implements AopProxy, Serializable {
 
 		private final int fixedInterceptorOffset;
 
-		public ProxyCallbackFilter(AdvisedSupport advised, Map<String, Integer> fixedInterceptorMap, int fixedInterceptorOffset) {
+		public ProxyCallbackFilter(
+				AdvisedSupport advised, Map<String, Integer> fixedInterceptorMap, int fixedInterceptorOffset) {
+
 			this.advised = advised;
 			this.fixedInterceptorMap = fixedInterceptorMap;
 			this.fixedInterceptorOffset = fixedInterceptorOffset;
@@ -859,7 +875,7 @@ class CglibAopProxy implements AopProxy, Serializable {
 					return INVOKE_TARGET;
 				}
 				Class<?> returnType = method.getReturnType();
-				if (returnType.isAssignableFrom(targetClass)) {
+				if (targetClass != null && returnType.isAssignableFrom(targetClass)) {
 					if (logger.isDebugEnabled()) {
 						logger.debug("Method return type is assignable from target type and " +
 								"may therefore return 'this' - using INVOKE_TARGET: " + method);
@@ -886,9 +902,6 @@ class CglibAopProxy implements AopProxy, Serializable {
 			}
 			ProxyCallbackFilter otherCallbackFilter = (ProxyCallbackFilter) other;
 			AdvisedSupport otherAdvised = otherCallbackFilter.advised;
-			if (this.advised == null || otherAdvised == null) {
-				return false;
-			}
 			if (this.advised.isFrozen() != otherAdvised.isFrozen()) {
 				return false;
 			}
@@ -922,12 +935,7 @@ class CglibAopProxy implements AopProxy, Serializable {
 		}
 
 		private boolean equalsAdviceClasses(Advisor a, Advisor b) {
-			Advice aa = a.getAdvice();
-			Advice ba = b.getAdvice();
-			if (aa == null || ba == null) {
-				return (aa == ba);
-			}
-			return (aa.getClass() == ba.getClass());
+			return (a.getAdvice().getClass() == b.getAdvice().getClass());
 		}
 
 		private boolean equalsPointcuts(Advisor a, Advisor b) {
@@ -944,9 +952,7 @@ class CglibAopProxy implements AopProxy, Serializable {
 			Advisor[] advisors = this.advised.getAdvisors();
 			for (Advisor advisor : advisors) {
 				Advice advice = advisor.getAdvice();
-				if (advice != null) {
-					hashCode = 13 * hashCode + advice.getClass().hashCode();
-				}
+				hashCode = 13 * hashCode + advice.getClass().hashCode();
 			}
 			hashCode = 13 * hashCode + (this.advised.isFrozen() ? 1 : 0);
 			hashCode = 13 * hashCode + (this.advised.isExposeProxy() ? 1 : 0);
@@ -966,7 +972,7 @@ class CglibAopProxy implements AopProxy, Serializable {
 
 		private final ClassLoader classLoader;
 
-		public ClassLoaderAwareUndeclaredThrowableStrategy(ClassLoader classLoader) {
+		public ClassLoaderAwareUndeclaredThrowableStrategy(@Nullable ClassLoader classLoader) {
 			super(UndeclaredThrowableException.class);
 			this.classLoader = classLoader;
 		}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -152,6 +152,7 @@ final class JdkDynamicAopProxy implements AopProxy, InvocationHandler, Serializa
 	 * unless a hook method throws an exception.
 	 */
 	@Override
+	@Nullable
 	public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
 		MethodInvocation invocation;
 		Object oldProxy = null;
@@ -249,7 +250,7 @@ final class JdkDynamicAopProxy implements AopProxy, InvocationHandler, Serializa
 	 * or a dynamic proxy wrapping a JdkDynamicAopProxy instance.
 	 */
 	@Override
-	public boolean equals(Object other) {
+	public boolean equals(@Nullable Object other) {
 		if (other == this) {
 			return true;
 		}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -220,7 +220,7 @@ public class ProxyFactoryBean extends ProxyCreatorSupport
 	}
 
 	@Override
-	public void setBeanClassLoader(@Nullable ClassLoader classLoader) {
+	public void setBeanClassLoader(ClassLoader classLoader) {
 		if (!this.classLoaderConfigured) {
 			this.proxyClassLoader = classLoader;
 		}
@@ -345,8 +345,10 @@ public class ProxyFactoryBean extends ProxyCreatorSupport
 		copy.copyConfigurationFrom(this, targetSource, freshAdvisorChain());
 		if (this.autodetectInterfaces && getProxiedInterfaces().length == 0 && !isProxyTargetClass()) {
 			// Rely on AOP infrastructure to tell us what interfaces to proxy.
-			copy.setInterfaces(
-					ClassUtils.getAllInterfacesForClass(targetSource.getTargetClass(), this.proxyClassLoader));
+			Class<?> targetClass = targetSource.getTargetClass();
+			if (targetClass != null) {
+				copy.setInterfaces(ClassUtils.getAllInterfacesForClass(targetClass, this.proxyClassLoader));
+			}
 		}
 		copy.setFrozen(this.freezeProxy);
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -69,7 +69,7 @@ public class ProxyProcessorSupport extends ProxyConfig implements Ordered, BeanC
 	 * {@link org.springframework.beans.factory.BeanFactory} for loading all bean classes.
 	 * This can be overridden here for specific proxies.
 	 */
-	public void setProxyClassLoader(ClassLoader classLoader) {
+	public void setProxyClassLoader(@Nullable ClassLoader classLoader) {
 		this.proxyClassLoader = classLoader;
 		this.classLoaderConfigured = (classLoader != null);
 	}
@@ -82,7 +82,7 @@ public class ProxyProcessorSupport extends ProxyConfig implements Ordered, BeanC
 	}
 
 	@Override
-	public void setBeanClassLoader(@Nullable ClassLoader classLoader) {
+	public void setBeanClassLoader(ClassLoader classLoader) {
 		if (!this.classLoaderConfigured) {
 			this.proxyClassLoader = classLoader;
 		}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -103,8 +103,8 @@ public class ReflectiveMethodInvocation implements ProxyMethodInvocation, Clonea
 	 * but would complicate the code. And it would work only for static pointcuts.
 	 */
 	protected ReflectiveMethodInvocation(
-			Object proxy, Object target, Method method, Object[] arguments,
-			Class<?> targetClass, List<Object> interceptorsAndDynamicMethodMatchers) {
+			Object proxy, @Nullable Object target, Method method, Object[] arguments,
+			@Nullable Class<?> targetClass, List<Object> interceptorsAndDynamicMethodMatchers) {
 
 		this.proxy = proxy;
 		this.target = target;
@@ -152,6 +152,7 @@ public class ReflectiveMethodInvocation implements ProxyMethodInvocation, Clonea
 
 
 	@Override
+	@Nullable
 	public Object proceed() throws Throwable {
 		//	We start with an index of -1 and increment early.
 		if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size() - 1) {
@@ -187,6 +188,7 @@ public class ReflectiveMethodInvocation implements ProxyMethodInvocation, Clonea
 	 * @return the return value of the joinpoint
 	 * @throws Throwable if invoking the joinpoint resulted in an exception
 	 */
+	@Nullable
 	protected Object invokeJoinpoint() throws Throwable {
 		return AopUtils.invokeJoinpointUsingReflection(this.target, this.method, this.arguments);
 	}
@@ -220,7 +222,7 @@ public class ReflectiveMethodInvocation implements ProxyMethodInvocation, Clonea
 	 * @see java.lang.Object#clone()
 	 */
 	@Override
-	public MethodInvocation invocableClone(Object... arguments) {
+	public MethodInvocation invocableClone(@Nullable Object... arguments) {
 		// Force initialization of the user attributes Map,
 		// for having a shared Map reference in the clone.
 		if (this.userAttributes == null) {

spring-aop/src/main/java/org/springframework/aop/framework/adapter/ThrowsAdviceInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -27,6 +27,7 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
 import org.springframework.aop.AfterAdvice;
+import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 
 /**
@@ -103,6 +104,7 @@ public class ThrowsAdviceInterceptor implements MethodInterceptor, AfterAdvice {
 	 * @param exception the exception thrown
 	 * @return a handler for the given exception type
 	 */
+	@Nullable
 	private Method getExceptionHandler(Throwable exception) {
 		Class<?> exceptionClass = exception.getClass();
 		if (logger.isTraceEnabled()) {

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -238,7 +238,7 @@ public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
 	}
 
 	@Override
-	public Object postProcessBeforeInstantiation(Class<?> beanClass, String beanName) throws BeansException {
+	public Object postProcessBeforeInstantiation(Class<?> beanClass, @Nullable String beanName) throws BeansException {
 		Object cacheKey = getCacheKey(beanClass, beanName);
 
 		if (beanName == null || !this.targetSourcedBeans.contains(beanName)) {
@@ -291,7 +291,7 @@ public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
 	 * @see #getAdvicesAndAdvisorsForBean
 	 */
 	@Override
-	public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
+	public Object postProcessAfterInitialization(@Nullable Object bean, String beanName) throws BeansException {
 		if (bean != null) {
 			Object cacheKey = getCacheKey(bean.getClass(), beanName);
 			if (!this.earlyProxyReferences.contains(cacheKey)) {
@@ -313,7 +313,7 @@ public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
 	 * @param beanName the bean name
 	 * @return the cache key for the given class and name
 	 */
-	protected Object getCacheKey(Class<?> beanClass, String beanName) {
+	protected Object getCacheKey(Class<?> beanClass, @Nullable String beanName) {
 		if (StringUtils.hasLength(beanName)) {
 			return (FactoryBean.class.isAssignableFrom(beanClass) ?
 					BeanFactory.FACTORY_BEAN_PREFIX + beanName : beanName);
@@ -330,7 +330,7 @@ public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
 	 * @param cacheKey the cache key for metadata access
 	 * @return a proxy wrapping the bean, or the raw bean instance as-is
 	 */
-	protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {
+	protected Object wrapIfNecessary(Object bean, @Nullable String beanName, Object cacheKey) {
 		if (beanName != null && this.targetSourcedBeans.contains(beanName)) {
 			return bean;
 		}
@@ -388,7 +388,7 @@ public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
 	 * @param beanName the name of the bean
 	 * @return whether to skip the given bean
 	 */
-	protected boolean shouldSkip(Class<?> beanClass, String beanName) {
+	protected boolean shouldSkip(Class<?> beanClass, @Nullable String beanName) {
 		return false;
 	}
 
@@ -435,8 +435,8 @@ public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
 	 * @return the AOP proxy for the bean
 	 * @see #buildAdvisors
 	 */
-	protected Object createProxy(
-			Class<?> beanClass, String beanName, Object[] specificInterceptors, TargetSource targetSource) {
+	protected Object createProxy(Class<?> beanClass, @Nullable String beanName,
+			@Nullable Object[] specificInterceptors, TargetSource targetSource) {
 
 		if (this.beanFactory instanceof ConfigurableListableBeanFactory) {
 			AutoProxyUtils.exposeTargetClass((ConfigurableListableBeanFactory) this.beanFactory, beanName, beanClass);
@@ -479,7 +479,7 @@ public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
 	 * @return whether the given bean should be proxied with its target class
 	 * @see AutoProxyUtils#shouldProxyTargetClass
 	 */
-	protected boolean shouldProxyTargetClass(Class<?> beanClass, String beanName) {
+	protected boolean shouldProxyTargetClass(Class<?> beanClass, @Nullable String beanName) {
 		return (this.beanFactory instanceof ConfigurableListableBeanFactory &&
 				AutoProxyUtils.shouldProxyTargetClass((ConfigurableListableBeanFactory) this.beanFactory, beanName));
 	}
@@ -506,7 +506,7 @@ public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
 	 * specific to this bean (may be empty, but not null)
 	 * @return the list of Advisors for the given bean
 	 */
-	protected Advisor[] buildAdvisors(String beanName, Object[] specificInterceptors) {
+	protected Advisor[] buildAdvisors(@Nullable String beanName, @Nullable Object[] specificInterceptors) {
 		// Handle prototypes correctly...
 		Advisor[] commonInterceptors = resolveInterceptorNames();
 
@@ -582,7 +582,8 @@ public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
 	 * @see #PROXY_WITHOUT_ADDITIONAL_INTERCEPTORS
 	 */
 	@Nullable
-	protected abstract Object[] getAdvicesAndAdvisorsForBean(
-			Class<?> beanClass, String beanName, @Nullable TargetSource customTargetSource) throws BeansException;
+	protected abstract Object[] getAdvicesAndAdvisorsForBean(Class<?> beanClass,
+			@Nullable String beanName, @Nullable TargetSource customTargetSource)
+			throws BeansException;
 
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -63,7 +63,7 @@ public abstract class AutoProxyUtils {
 	 * @param beanName the name of the bean
 	 * @return whether the given bean should be proxied with its target class
 	 */
-	public static boolean shouldProxyTargetClass(ConfigurableListableBeanFactory beanFactory, String beanName) {
+	public static boolean shouldProxyTargetClass(ConfigurableListableBeanFactory beanFactory, @Nullable String beanName) {
 		if (beanName != null && beanFactory.containsBeanDefinition(beanName)) {
 			BeanDefinition bd = beanFactory.getBeanDefinition(beanName);
 			return Boolean.TRUE.equals(bd.getAttribute(PRESERVE_TARGET_CLASS_ATTRIBUTE));
@@ -81,7 +81,7 @@ public abstract class AutoProxyUtils {
 	 * @see org.springframework.beans.factory.BeanFactory#getType(String)
 	 */
 	@Nullable
-	public static Class<?> determineTargetClass(ConfigurableListableBeanFactory beanFactory, String beanName) {
+	public static Class<?> determineTargetClass(ConfigurableListableBeanFactory beanFactory, @Nullable String beanName) {
 		if (beanName == null) {
 			return null;
 		}
@@ -102,7 +102,9 @@ public abstract class AutoProxyUtils {
 	 * @param targetClass the corresponding target class
 	 * @since 4.2.3
 	 */
-	static void exposeTargetClass(ConfigurableListableBeanFactory beanFactory, String beanName, Class<?> targetClass) {
+	static void exposeTargetClass(ConfigurableListableBeanFactory beanFactory, @Nullable String beanName,
+			Class<?> targetClass) {
+
 		if (beanName != null && beanFactory.containsBeanDefinition(beanName)) {
 			beanFactory.getMergedBeanDefinition(beanName).setAttribute(ORIGINAL_TARGET_CLASS_ATTRIBUTE, targetClass);
 		}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -20,6 +20,8 @@ import java.lang.reflect.Method;
 
 import org.aopalliance.intercept.MethodInvocation;
 
+import org.springframework.lang.Nullable;
+
 /**
  * Base class for monitoring interceptors, such as performance monitors.
  * Provides {@code prefix} and {@code suffix} properties
@@ -50,7 +52,7 @@ public abstract class AbstractMonitoringInterceptor extends AbstractTraceInterce
 	 * Set the text that will get appended to the trace data.
 	 * <p>Default is none.
 	 */
-	public void setPrefix(String prefix) {
+	public void setPrefix(@Nullable String prefix) {
 		this.prefix = (prefix != null ? prefix : "");
 	}
 
@@ -65,7 +67,7 @@ public abstract class AbstractMonitoringInterceptor extends AbstractTraceInterce
 	 * Set the text that will get prepended to the trace data.
 	 * <p>Default is none.
 	 */
-	public void setSuffix(String suffix) {
+	public void setSuffix(@Nullable String suffix) {
 		this.suffix = (suffix != null ? suffix : "");
 	}
 

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

@@ -87,7 +87,7 @@ public abstract class AsyncExecutionAspectSupport implements BeanFactoryAware {
 	 * executor has been requested via a qualifier on the async method, in which case the
 	 * executor will be looked up at invocation time against the enclosing bean factory
 	 */
-	public AsyncExecutionAspectSupport(Executor defaultExecutor) {
+	public AsyncExecutionAspectSupport(@Nullable Executor defaultExecutor) {
 		this(defaultExecutor, new SimpleAsyncUncaughtExceptionHandler());
 	}
 
@@ -99,7 +99,7 @@ public abstract class AsyncExecutionAspectSupport implements BeanFactoryAware {
 	 * executor will be looked up at invocation time against the enclosing bean factory
 	 * @param exceptionHandler the {@link AsyncUncaughtExceptionHandler} to use
 	 */
-	public AsyncExecutionAspectSupport(Executor defaultExecutor, AsyncUncaughtExceptionHandler exceptionHandler) {
+	public AsyncExecutionAspectSupport(@Nullable Executor defaultExecutor, AsyncUncaughtExceptionHandler exceptionHandler) {
 		this.defaultExecutor = defaultExecutor;
 		this.exceptionHandler = exceptionHandler;
 	}
@@ -196,7 +196,7 @@ public abstract class AsyncExecutionAspectSupport implements BeanFactoryAware {
 	 * @see #getExecutorQualifier(Method)
 	 */
 	@Nullable
-	protected Executor findQualifiedExecutor(BeanFactory beanFactory, String qualifier) {
+	protected Executor findQualifiedExecutor(@Nullable BeanFactory beanFactory, String qualifier) {
 		if (beanFactory == null) {
 			throw new IllegalStateException("BeanFactory must be set on " + getClass().getSimpleName() +
 					" to access qualified executor '" + qualifier + "'");
@@ -217,7 +217,7 @@ public abstract class AsyncExecutionAspectSupport implements BeanFactoryAware {
 	 * @see #DEFAULT_TASK_EXECUTOR_BEAN_NAME
 	 */
 	@Nullable
-	protected Executor getDefaultExecutor(BeanFactory beanFactory) {
+	protected Executor getDefaultExecutor(@Nullable BeanFactory beanFactory) {
 		if (beanFactory != null) {
 			try {
 				// Search for TaskExecutor bean... not plain Executor since that would

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -31,6 +31,7 @@ import org.springframework.core.BridgeMethodResolver;
 import org.springframework.core.Ordered;
 import org.springframework.core.task.AsyncTaskExecutor;
 import org.springframework.core.task.SimpleAsyncTaskExecutor;
+import org.springframework.lang.Nullable;
 import org.springframework.util.ClassUtils;
 
 /**
@@ -73,7 +74,7 @@ public class AsyncExecutionInterceptor extends AsyncExecutionAspectSupport imple
 	 * or {@link java.util.concurrent.ExecutorService}) to delegate to;
 	 * as of 4.2.6, a local executor for this interceptor will be built otherwise
 	 */
-	public AsyncExecutionInterceptor(Executor defaultExecutor) {
+	public AsyncExecutionInterceptor(@Nullable Executor defaultExecutor) {
 		super(defaultExecutor);
 	}
 
@@ -84,7 +85,7 @@ public class AsyncExecutionInterceptor extends AsyncExecutionAspectSupport imple
 	 * as of 4.2.6, a local executor for this interceptor will be built otherwise
 	 * @param exceptionHandler the {@link AsyncUncaughtExceptionHandler} to use
 	 */
-	public AsyncExecutionInterceptor(Executor defaultExecutor, AsyncUncaughtExceptionHandler exceptionHandler) {
+	public AsyncExecutionInterceptor(@Nullable Executor defaultExecutor, AsyncUncaughtExceptionHandler exceptionHandler) {
 		super(defaultExecutor, exceptionHandler);
 	}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -292,7 +292,7 @@ public class CustomizableTraceInterceptor extends AbstractTraceInterceptor {
 	 * at {@code TRACE} level. Sub-classes can override this method
 	 * to control which level the message is written at.
 	 */
-	protected void writeToLog(Log logger, String message, Throwable ex) {
+	protected void writeToLog(Log logger, String message, @Nullable Throwable ex) {
 		if (ex != null) {
 			logger.trace(message, ex);
 		}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -22,6 +22,7 @@ import org.springframework.beans.factory.config.BeanDefinitionHolder;
 import org.springframework.beans.factory.support.AbstractBeanDefinition;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.support.RootBeanDefinition;
+import org.springframework.lang.Nullable;
 
 /**
  * Utility class for creating a scoped proxy.
@@ -102,7 +103,7 @@ public abstract class ScopedProxyUtils {
 	 * bean within a scoped proxy.
 	 * @since 4.1.4
 	 */
-	public static boolean isScopedTarget(String beanName) {
+	public static boolean isScopedTarget(@Nullable String beanName) {
 		return (beanName != null && beanName.startsWith(TARGET_NAME_PREFIX));
 	}
 

spring-aop/src/main/java/org/springframework/aop/support/AbstractBeanFactoryPointcutAdvisor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -101,11 +101,13 @@ public abstract class AbstractBeanFactoryPointcutAdvisor extends AbstractPointcu
 	@Override
 	public Advice getAdvice() {
 		Advice advice = this.advice;
-		if (advice != null || this.adviceBeanName == null) {
+		if (advice != null) {
 			return advice;
 		}
 
+		Assert.state(this.adviceBeanName != null, "'adviceBeanName' must be specified");
 		Assert.state(this.beanFactory != null, "BeanFactory must be set to resolve 'adviceBeanName'");
+
 		if (this.beanFactory.isSingleton(this.adviceBeanName)) {
 			// Rely on singleton semantics provided by the factory.
 			advice = this.beanFactory.getBean(this.adviceBeanName, Advice.class);

spring-aop/src/main/java/org/springframework/aop/support/AopUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -127,7 +127,10 @@ public abstract class AopUtils {
 	 * @since 4.3
 	 * @see MethodIntrospector#selectInvocableMethod(Method, Class)
 	 */
-	public static Method selectInvocableMethod(Method method, Class<?> targetType) {
+	public static Method selectInvocableMethod(Method method, @Nullable Class<?> targetType) {
+		if (targetType == null) {
+			return method;
+		}
 		Method methodToUse = MethodIntrospector.selectInvocableMethod(method, targetType);
 		if (Modifier.isPrivate(methodToUse.getModifiers()) && !Modifier.isStatic(methodToUse.getModifiers()) &&
 				SpringProxy.class.isAssignableFrom(targetType)) {
@@ -143,7 +146,7 @@ public abstract class AopUtils {
 	 * Determine whether the given method is an "equals" method.
 	 * @see java.lang.Object#equals
 	 */
-	public static boolean isEqualsMethod(Method method) {
+	public static boolean isEqualsMethod(@Nullable Method method) {
 		return ReflectionUtils.isEqualsMethod(method);
 	}
 
@@ -151,7 +154,7 @@ public abstract class AopUtils {
 	 * Determine whether the given method is a "hashCode" method.
 	 * @see java.lang.Object#hashCode
 	 */
-	public static boolean isHashCodeMethod(Method method) {
+	public static boolean isHashCodeMethod(@Nullable Method method) {
 		return ReflectionUtils.isHashCodeMethod(method);
 	}
 
@@ -159,7 +162,7 @@ public abstract class AopUtils {
 	 * Determine whether the given method is a "toString" method.
 	 * @see java.lang.Object#toString()
 	 */
-	public static boolean isToStringMethod(Method method) {
+	public static boolean isToStringMethod(@Nullable Method method) {
 		return ReflectionUtils.isToStringMethod(method);
 	}
 
@@ -167,7 +170,7 @@ public abstract class AopUtils {
 	 * Determine whether the given method is a "finalize" method.
 	 * @see java.lang.Object#finalize()
 	 */
-	public static boolean isFinalizeMethod(Method method) {
+	public static boolean isFinalizeMethod(@Nullable Method method) {
 		return (method != null && method.getName().equals("finalize") &&
 				method.getParameterCount() == 0);
 	}
@@ -326,7 +329,7 @@ public abstract class AopUtils {
 	 * @throws org.springframework.aop.AopInvocationException in case of a reflection error
 	 */
 	@Nullable
-	public static Object invokeJoinpointUsingReflection(Object target, Method method, Object[] args)
+	public static Object invokeJoinpointUsingReflection(@Nullable Object target, Method method, Object[] args)
 			throws Throwable {
 
 		// Use reflection to invoke the method.

spring-aop/src/main/java/org/springframework/aop/support/DefaultBeanFactoryPointcutAdvisor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -17,6 +17,7 @@
 package org.springframework.aop.support;
 
 import org.springframework.aop.Pointcut;
+import org.springframework.lang.Nullable;
 
 /**
  * Concrete BeanFactory-based PointcutAdvisor that allows for any Advice
@@ -43,7 +44,7 @@ public class DefaultBeanFactoryPointcutAdvisor extends AbstractBeanFactoryPointc
 	 * <p>Default is {@code Pointcut.TRUE}.
 	 * @see #setAdviceBeanName
 	 */
-	public void setPointcut(Pointcut pointcut) {
+	public void setPointcut(@Nullable Pointcut pointcut) {
 		this.pointcut = (pointcut != null ? pointcut : Pointcut.TRUE);
 	}
 

spring-aop/src/main/java/org/springframework/aop/support/DefaultPointcutAdvisor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -21,6 +21,7 @@ import java.io.Serializable;
 import org.aopalliance.aop.Advice;
 
 import org.springframework.aop.Pointcut;
+import org.springframework.lang.Nullable;
 
 /**
  * Convenient Pointcut-driven Advisor implementation.
@@ -73,7 +74,7 @@ public class DefaultPointcutAdvisor extends AbstractGenericPointcutAdvisor imple
 	 * <p>Default is {@code Pointcut.TRUE}.
 	 * @see #setAdvice
 	 */
-	public void setPointcut(Pointcut pointcut) {
+	public void setPointcut(@Nullable Pointcut pointcut) {
 		this.pointcut = (pointcut != null ? pointcut : Pointcut.TRUE);
 	}
 

spring-aop/src/main/java/org/springframework/aop/support/ExpressionPointcut.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2006 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -17,6 +17,7 @@
 package org.springframework.aop.support;
 
 import org.springframework.aop.Pointcut;
+import org.springframework.lang.Nullable;
 
 /**
  * Interface to be implemented by pointcuts that use String expressions.
@@ -29,6 +30,7 @@ public interface ExpressionPointcut extends Pointcut {
 	/**
 	 * Return the String expression for this pointcut.
 	 */
+	@Nullable
 	String getExpression();
 
 }

spring-aop/src/main/java/org/springframework/aop/support/MethodMatchers.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -125,11 +125,11 @@ public abstract class MethodMatchers {
 					(matchesClass2(targetClass) && this.mm2.matches(method, targetClass));
 		}
 
-		protected boolean matchesClass1(Class<?> targetClass) {
+		protected boolean matchesClass1(@Nullable Class<?> targetClass) {
 			return true;
 		}
 
-		protected boolean matchesClass2(Class<?> targetClass) {
+		protected boolean matchesClass2(@Nullable Class<?> targetClass) {
 			return true;
 		}
 
@@ -183,13 +183,13 @@ public abstract class MethodMatchers {
 		}
 
 		@Override
-		protected boolean matchesClass1(Class<?> targetClass) {
-			return this.cf1.matches(targetClass);
+		protected boolean matchesClass1(@Nullable Class<?> targetClass) {
+			return (targetClass != null && this.cf1.matches(targetClass));
 		}
 
 		@Override
-		protected boolean matchesClass2(Class<?> targetClass) {
-			return this.cf2.matches(targetClass);
+		protected boolean matchesClass2(@Nullable Class<?> targetClass) {
+			return (targetClass != null && this.cf2.matches(targetClass));
 		}
 
 		@Override

spring-aop/src/main/java/org/springframework/aop/support/NameMatchMethodPointcut.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -56,7 +56,7 @@ public class NameMatchMethodPointcut extends StaticMethodMatcherPointcut impleme
 	 * Matching will be the union of all these; if any match,
 	 * the pointcut matches.
 	 */
-	public void setMappedNames(String... mappedNames) {
+	public void setMappedNames(@Nullable String... mappedNames) {
 		this.mappedNames = new LinkedList<>();
 		if (mappedNames != null) {
 			this.mappedNames.addAll(Arrays.asList(mappedNames));

spring-aop/src/main/java/org/springframework/aop/support/RegexpMethodPointcutAdvisor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -21,7 +21,6 @@ import java.io.Serializable;
 import org.aopalliance.aop.Advice;
 
 import org.springframework.aop.Pointcut;
-import org.springframework.lang.Nullable;
 import org.springframework.util.ObjectUtils;
 
 /**
@@ -133,7 +132,6 @@ public class RegexpMethodPointcutAdvisor extends AbstractGenericPointcutAdvisor
 	 * will be used.
 	 * @return the Pointcut instance (never {@code null})
 	 */
-	@Nullable
 	protected AbstractRegexpMethodPointcut createPointcut() {
 		return new JdkRegexpMethodPointcut();
 	}

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

@@ -69,8 +69,8 @@ public class AnnotationMatchingPointcut implements Pointcut {
 	 * @param methodAnnotationType the annotation type to look for at the method level
 	 * (can be {@code null})
 	 */
-	public AnnotationMatchingPointcut(
-			@Nullable Class<? extends Annotation> classAnnotationType, @Nullable Class<? extends Annotation> methodAnnotationType) {
+	public AnnotationMatchingPointcut(@Nullable Class<? extends Annotation> classAnnotationType,
+			@Nullable Class<? extends Annotation> methodAnnotationType) {
 
 		this(classAnnotationType, methodAnnotationType, false);
 	}
@@ -87,8 +87,8 @@ public class AnnotationMatchingPointcut implements Pointcut {
 	 * @see AnnotationClassFilter#AnnotationClassFilter(Class, boolean)
 	 * @see AnnotationMethodMatcher#AnnotationMethodMatcher(Class, boolean)
 	 */
-	public AnnotationMatchingPointcut(Class<? extends Annotation> classAnnotationType,
-			Class<? extends Annotation> methodAnnotationType, boolean checkInherited) {
+	public AnnotationMatchingPointcut(@Nullable Class<? extends Annotation> classAnnotationType,
+			@Nullable Class<? extends Annotation> methodAnnotationType, boolean checkInherited) {
 
 		Assert.isTrue((classAnnotationType != null || methodAnnotationType != null),
 				"Either Class annotation type or Method annotation type needs to be specified (or both)");

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -24,6 +24,7 @@ import org.apache.commons.logging.LogFactory;
 import org.springframework.aop.TargetSource;
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanFactoryAware;
+import org.springframework.util.ClassUtils;
 import org.springframework.util.ObjectUtils;
 
 /**
@@ -129,9 +130,7 @@ public abstract class AbstractBeanFactoryBasedTargetSource implements TargetSour
 					logger.trace("Getting bean with name '" + this.targetBeanName + "' in order to determine type");
 				}
 				Object beanInstance = this.beanFactory.getBean(this.targetBeanName);
-				if (beanInstance != null) {
-					this.targetClass = beanInstance.getClass();
-				}
+				this.targetClass = beanInstance.getClass();
 			}
 		}
 		return this.targetClass;