src/java.base/share/classes/java/lang/RuntimeException.java

@@ -39,10 +39,11 @@
  * @author  Frank Yellin
  * @jls 11.2 Compile-Time Checking of Exceptions
  * @since   1.0
  */
 public class RuntimeException extends Exception {
+    @java.io.Serial
     static final long serialVersionUID = -7034897190745766939L;
 
     /** Constructs a new runtime exception with {@code null} as its
      * detail message.  The cause is not initialized, and may subsequently be
      * initialized by a call to {@link #initCause}.