diff -r 18863bf3501f -r e0b8b019d2f5 src/java.base/share/classes/java/util/UnknownFormatFlagsException.java
--- a/src/java.base/share/classes/java/util/UnknownFormatFlagsException.java	Thu Aug 29 18:52:30 2019 -0400
+++ b/src/java.base/share/classes/java/util/UnknownFormatFlagsException.java	Thu Aug 29 16:31:34 2019 -0700
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -36,6 +36,7 @@
  */
 public class UnknownFormatFlagsException extends IllegalFormatException {
 
+    @java.io.Serial
     private static final long serialVersionUID = 19370506L;
 
     private String flags;