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

@@ -35,10 +35,11 @@
  * @since 1.5
  */
 public class FormatFlagsConversionMismatchException
     extends IllegalFormatException
 {
+    @java.io.Serial
     private static final long serialVersionUID = 19120414L;
 
     private String f;
 
     private char c;