--- old/src/java.base/share/classes/sun/net/TelnetProtocolException.java	2019-08-27 17:29:29.014324386 -0700
+++ new/src/java.base/share/classes/sun/net/TelnetProtocolException.java	2019-08-27 17:29:28.806324386 -0700
@@ -35,6 +35,7 @@
  */
 
 public class TelnetProtocolException extends IOException {
+    @java.io.Serial
     private static final long serialVersionUID = 8509127047257111343L;
 
     public TelnetProtocolException(String s) {