--- old/src/java.base/share/classes/java/util/JumboEnumSet.java	2019-08-27 17:29:04.994324386 -0700
+++ new/src/java.base/share/classes/java/util/JumboEnumSet.java	2019-08-27 17:29:04.830324386 -0700
@@ -34,6 +34,7 @@
  * @serial exclude
  */
 class JumboEnumSet<E extends Enum<E>> extends EnumSet<E> {
+    @java.io.Serial
     private static final long serialVersionUID = 334349849919042784L;
 
     /**