src/java.base/share/classes/java/net/ProtocolException.java

*** 34,43 ****
--- 34,44 ----
   * @author  Chris Warth
   * @since   1.0
   */
  public
  class ProtocolException extends IOException {
+     @java.io.Serial
      private static final long serialVersionUID = -6098449442062388080L;
  
      /**
       * Constructs a new {@code ProtocolException} with the
       * specified detail message.