Fix a NullPointerException.


git-svn-id: https://svn.apache.org/repos/asf/sis/branches/JDK8@1627536 13f79535-47bb-0310-9956-ffa450edef68
Merge the NullPointerException fix.


git-svn-id: https://svn.apache.org/repos/asf/sis/branches/JDK7@1627537 13f79535-47bb-0310-9956-ffa450edef68