Fix serialization compiler warnings with Java 18

As of Java 18, the serial lint warning in javac has been expanded to
check for class fields that are not marked as `Serializable`.
See https://www.oracle.com/java/technologies/javase/18all-relnotes.html#JDK-8202056

In the Spring Framework codebase, this can happen with `Map`, `Set` or
`List` attributes which are often assigned with an unmodifiable
implementation variant. Such implementations are `Serializable` but
cannot be used as field types.

This commit ensures that the following changes are applied:
* fields are marked as transient if they can't be serialized
* classes are marked as `Serializable` if this was missing
* `@SuppressWarnings("serial")` is applied where relevant

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

@@ -72,12 +72,14 @@ public class AdvisedSupport extends ProxyConfig implements Advised {
 
 
 	/** Package-protected to allow direct access for efficiency. */
+	@SuppressWarnings("serial")
 	TargetSource targetSource = EMPTY_TARGET_SOURCE;
 
 	/** Whether the Advisors are already filtered for the specific target class. */
 	private boolean preFiltered = false;
 
 	/** The AdvisorChainFactory to use. */
+	@SuppressWarnings("serial")
 	AdvisorChainFactory advisorChainFactory = new DefaultAdvisorChainFactory();
 
 	/** Cache with Method as key and advisor chain List as value. */
@@ -87,12 +89,14 @@ public class AdvisedSupport extends ProxyConfig implements Advised {
 	 * Interfaces to be implemented by the proxy. Held in List to keep the order
 	 * of registration, to create JDK proxy with specified order of interfaces.
 	 */
+	@SuppressWarnings("serial")
 	private List<Class<?>> interfaces = new ArrayList<>();
 
 	/**
 	 * List of Advisors. If an Advice is added, it will be wrapped
 	 * in an Advisor before being added to this List.
 	 */
+	@SuppressWarnings("serial")
 	private List<Advisor> advisors = new ArrayList<>();
 
 

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

@@ -46,8 +46,10 @@ public class ComposablePointcut implements Pointcut, Serializable {
 	/** use serialVersionUID from Spring 1.2 for interoperability. */
 	private static final long serialVersionUID = -2743223737633663832L;
 
+	@SuppressWarnings("serial")
 	private ClassFilter classFilter;
 
+	@SuppressWarnings("serial")
 	private MethodMatcher methodMatcher;
 
 

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

@@ -54,7 +54,7 @@ public abstract class AbstractBeanFactoryBasedTargetSource implements TargetSour
 
 
 	/** Logger available to subclasses. */
-	protected final Log logger = LogFactory.getLog(getClass());
+	protected final transient Log logger = LogFactory.getLog(getClass());
 
 	/** Name of the target bean we will create on each invocation. */
 	private String targetBeanName;
@@ -66,6 +66,7 @@ public abstract class AbstractBeanFactoryBasedTargetSource implements TargetSour
 	 * BeanFactory that owns this TargetSource. We need to hold onto this
 	 * reference so that we can create new prototype instances as necessary.
 	 */
+	@SuppressWarnings("serial")
 	private BeanFactory beanFactory;
 
 

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

@@ -42,6 +42,7 @@ public class HotSwappableTargetSource implements TargetSource, Serializable {
 
 
 	/** The current target object. */
+	@SuppressWarnings("serial")
 	private Object target;
 
 

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

@@ -42,6 +42,7 @@ public class SingletonTargetSource implements TargetSource, Serializable {
 
 
 	/** Target cached and invoked using reflection. */
+	@SuppressWarnings("serial")
 	private final Object target;