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

@@ -31,10 +31,11 @@
  *
  * @since 1.5
  */
 public class IllegalFormatWidthException extends IllegalFormatException {
 
+    @java.io.Serial
     private static final long serialVersionUID = 16660902L;
 
     private int w;
 
     /**