hg: jdk9/sandbox/jdk: 8147772: Update KerberosTicket to describe behavior if it has been destroyed and fix NullPointerExceptions

[chris.hegarty at oracle.com]

Changeset: 7bcaf8487c69
Author:    weijun
Date:      2016-02-17 11:23 +0800
URL:       http://hg.openjdk.java.net/jdk9/sandbox/jdk/rev/7bcaf8487c69

8147772: Update KerberosTicket to describe behavior if it has been destroyed and fix NullPointerExceptions
Reviewed-by: mullan

! src/java.security.jgss/share/classes/javax/security/auth/kerberos/KerberosTicket.java
! test/javax/security/auth/kerberos/KerberosTixDateTest.java