src/java.base/share/classes/java/util/EventObject.java

@@ -36,10 +36,11 @@
  * @since 1.1
  */
 
 public class EventObject implements java.io.Serializable {
 
+    @java.io.Serial
     private static final long serialVersionUID = 5516075349620653480L;
 
     /**
      * The object on which the Event initially occurred.
      */