diff a/src/java.security.jgss/share/classes/javax/security/auth/kerberos/KerberosTicket.java b/src/java.security.jgss/share/classes/javax/security/auth/kerberos/KerberosTicket.java
--- a/src/java.security.jgss/share/classes/javax/security/auth/kerberos/KerberosTicket.java
+++ b/src/java.security.jgss/share/classes/javax/security/auth/kerberos/KerberosTicket.java
@@ -1,7 +1,7 @@
 /*
- * Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
@@ -837,10 +837,17 @@
         }
 
         return true;
     }
 
+    /**
+     * Restores the state of this object from the stream.
+     *
+     * @param  s the {@code ObjectInputStream} from which data is read
+     * @throws IOException if an I/O error occurs
+     * @throws ClassNotFoundException if a serialized class cannot be loaded
+     */
     private void readObject(ObjectInputStream s)
             throws IOException, ClassNotFoundException {
         s.defaultReadObject();
         if (sessionKey == null) {
            throw new InvalidObjectException("Session key cannot be null");
