Fix tests by allowing for the null return.

git-svn-id: https://svn.apache.org/repos/asf/cxf/trunk@1461738 13f79535-47bb-0310-9956-ffa450edef68
Output a better "message" into the exception.

git-svn-id: https://svn.apache.org/repos/asf/cxf/trunk@1461739 13f79535-47bb-0310-9956-ffa450edef68