null pointer error when GET request for /restconf/operational data fails.

Where the netconf controller is called 'controller-config_xrvr' a GET request to the URL resulted in a 500 error. We believe that this is because the response times out but this is not clear from the response. However filtering the response to request a smaller subtree resulted in a successful operation.

http://localhost:8080/restconf/operational/opendaylight-inventory:nodes/node/<controller-config_xrvr>/yang-ext:mount/

Expected Result
HTTP STATUS 200 and a JSON or XML reporesentation of the tre.

Actual Result

HTTP STATUS 500 and null pointer error.

SUCCESSFUL request for subtree

http://localhost:8080/restconf/operational/opendaylight-inventory:nodes/node/controller-config_xrvr/yang-ext:mount/Cisco-IOS-XR-aaa-locald-admin-cfg:aaa/Cisco-IOS-XR-aaa-locald-admin-cfg:usernames

Test Env

org.opendaylight.controller.version = 0.1
org.opendaylight.controller.build.scm.version = d04b6dc0d4f1eb7e53b95048d41bd11ff35a3fa9
org.opendaylight.controller.build.user = jenkins-controller
org.opendaylight.controller.build.workspace = **********
org.opendaylight.controller.build.timestamp = 1406427010958
org.opendaylight.controller.build.machine = **********
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