Make getters and setters null-safety consistent

This commit ensure that null-safety is consistent between
getters and setters in order to be able to provide beans
with properties with a common type when type safety is
taken in account like with Kotlin.

It also add a few missing property level @Nullable
annotations.

Issue: SPR-15792

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

@@ -34,7 +34,7 @@ public class AspectJExpressionPointcutAdvisor extends AbstractGenericPointcutAdv
 	private final AspectJExpressionPointcut pointcut = new AspectJExpressionPointcut();
 
 
-	public void setExpression(String expression) {
+	public void setExpression(@Nullable String expression) {
 		this.pointcut.setExpression(expression);
 	}
 
@@ -43,7 +43,7 @@ public class AspectJExpressionPointcutAdvisor extends AbstractGenericPointcutAdv
 		return this.pointcut.getExpression();
 	}
 
-	public void setLocation(String location) {
+	public void setLocation(@Nullable String location) {
 		this.pointcut.setLocation(location);
 	}
 

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

@@ -203,7 +203,7 @@ public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
 	}
 
 	@Override
-	public void setBeanFactory(BeanFactory beanFactory) {
+	public void setBeanFactory(@Nullable BeanFactory beanFactory) {
 		this.beanFactory = beanFactory;
 	}
 

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

@@ -70,7 +70,7 @@ public class DefaultAdvisorAutoProxyCreator extends AbstractAdvisorAutoProxyCrea
 	 * references. Default value is the bean name of this object + a dot.
 	 * @param advisorBeanNamePrefix the exclusion prefix
 	 */
-	public void setAdvisorBeanNamePrefix(String advisorBeanNamePrefix) {
+	public void setAdvisorBeanNamePrefix(@Nullable String advisorBeanNamePrefix) {
 		this.advisorBeanNamePrefix = advisorBeanNamePrefix;
 	}
 

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

@@ -63,7 +63,7 @@ public abstract class AbstractBeanFactoryPointcutAdvisor extends AbstractPointcu
 	 * of the advisor.
 	 * @see #getAdvice()
 	 */
-	public void setAdviceBeanName(String adviceBeanName) {
+	public void setAdviceBeanName(@Nullable String adviceBeanName) {
 		this.adviceBeanName = adviceBeanName;
 	}
 

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

@@ -43,7 +43,7 @@ public abstract class AbstractExpressionPointcut implements ExpressionPointcut,
 	/**
 	 * Set the location for debugging.
 	 */
-	public void setLocation(String location) {
+	public void setLocation(@Nullable String location) {
 		this.location = location;
 	}
 
@@ -58,7 +58,7 @@ public abstract class AbstractExpressionPointcut implements ExpressionPointcut,
 		return this.location;
 	}
 
-	public void setExpression(String expression) {
+	public void setExpression(@Nullable String expression) {
 		this.expression = expression;
 		try {
 			onSetExpression(expression);
@@ -82,7 +82,7 @@ public abstract class AbstractExpressionPointcut implements ExpressionPointcut,
 	 * @throws IllegalArgumentException if the expression is invalid
 	 * @see #setExpression
 	 */
-	protected void onSetExpression(String expression) throws IllegalArgumentException {
+	protected void onSetExpression(@Nullable String expression) throws IllegalArgumentException {
 	}
 
 	/**