src/share/classes/sun/awt/CausedFocusEvent.java

@@ -33,10 +33,11 @@
  * be mouse press, traversal, activation, and so on - all causes are described as Cause enum. The
  * event with the cause can be constructed in two ways - explicitly through constructor of
  * CausedFocusEvent class or implicitly, by calling appropriate requestFocusXXX method with "cause"
  * parameter. The default cause is UNKNOWN.
  */
+@SuppressWarnings("serial")
 public class CausedFocusEvent extends FocusEvent {
     public enum Cause {
         UNKNOWN,
         MOUSE_EVENT,
         TRAVERSAL,