--- old/src/java.base/share/classes/java/util/UnknownFormatConversionException.java	2019-08-27 17:29:15.994324386 -0700
+++ new/src/java.base/share/classes/java/util/UnknownFormatConversionException.java	2019-08-27 17:29:15.826324386 -0700
@@ -36,6 +36,7 @@
  */
 public class UnknownFormatConversionException extends IllegalFormatException {
 
+    @java.io.Serial
     private static final long serialVersionUID = 19060418L;
 
     private String s;