This might be a permission issue. Checking the username and password in place and then the below link might help:
https://stackoverflow.com/questions/9078726/cxf-client-exception-interceptor-for-xxx-has-thrown-exce...
"After debugging in the cxf code and seeking help in the cxf mailing list, I finally solved this problem. The problem is caused by the inbound message, the http message lacks the content-type header, which causes the CXF fail to create an XMLStreamReader, and then failed to read the content, thus a NullPointerException is thrown. Many thanks to the guys in the CXF community!
I asked a question and got answer there: http://cxf.547215.n5.nabble.com/CXF-client-exception-Interceptor-for-XXX-has-thrown-exception-unwind..."
In your case some other parameter might be null/missing and that might be causing the issue. Debugging will help you to find out what exactly is not in place.