Can't work this one out.

matching policy triggers a query which is sent to the rest driver as
Code:
<nds dtdversion="4.0" ndsversion="8.x">
  <source>
    <product edition="Standard" version="4.5.5.0">DirXML</product>
    <contact>NetIQ Corporation</contact>
  </source>
  <input>
    <driver-operation-data class-name="User" command="query" event-id="0">
      <request>
        <url-token filter="?search-id=ausername"/>
        <header content-type="application/json"/>
        <value>{"scope":"subtree","event-id":"0","class-name":"User","search-class":["User"],"search-attr":[{"CN":"ausername"}],"read-attr":[""]}</value>
      </request>
    </driver-operation-data>
  </input>
</nds>
Response is success

Code:
<nds dtdversion="3.0">
  <source>
    <product build="20150722_0750" version="1.0.0.0">Identity Manager REST Driver</product>
    <contact>NetIQ Corporation.</contact>
  </source>
  <output>
    <status event-id="0" level="success" type="driver-general">
      <driver-operation-data class-name="User" command="query" dest-dn="" event-id="0">
        <response>
          <url-token filter="?search-id=ausername"/>
          <header content-type="application/json"/>
          <value>{"totalResults":1,"results":[{"CN":"ausername","preferredGivenName":"First","preferredSurname":"Last","UofaEmail":"first.last@sit.corp.edu"}]}</value>
        </response>
      </driver-operation-data>
    </status>
  </output>
</nds>
JSON is converted fine to XDS which prodcues

Code:
<nds dtdversion="3.0">
  <source>
    <product build="20150722_0750" version="1.0.0.0">Identity Manager REST Driver</product>
    <contact>NetIQ Corporation.</contact>
  </source>
  <output>
    <status event-id="0" level="success" type="driver-general"/>
    <instance event-id="0">
      <attr attr-name="CN">
        <value type="string">ausername</value>
      </attr>
      <attr attr-name="preferredGivenName">
        <value type="string">First</value>
      </attr>
      <attr attr-name="preferredSurname">
        <value type="string">Last</value>
      </attr>
      <attr attr-name="UofaEmail">
        <value type="string">first.last@sit.corp.edu</value>
      </attr>
    </instance>
  </output>
</nds>
It goes through the mapping policy successfully to map UofAEmail to Internet Email Address but then I get the following, any ideas?

Code:
<nds dtdversion="3.0">
  <source>
    <product build="20150722_0750" version="1.0.0.0">Identity Manager REST Driver</product>
    <contact>NetIQ Corporation.</contact>
  </source>
  <output>
    <status event-id="0" level="success" type="driver-general"/>
    <instance event-id="0">
      <attr attr-name="CN">
        <value type="string">ausername</value>
      </attr>
      <attr attr-name="preferredGivenName">
        <value type="string">First</value>
      </attr>
      <attr attr-name="preferredSurname">
        <value type="string">Last</value>
      </attr>
      <attr attr-name="Internet EMail Address">
        <value type="string">first.last@sit.corp.edu</value>
      </attr>
    </instance>
  </output>
</nds>
[05/16/17 16:17:03.337]:IDMREST ST:
DirXML Log Event -------------------
     Driver:   \SITUOFAIDV\RESOURCES\Driver Set\Course Credits REST Driver
     Channel:  Subscriber
     Object:   \SITUOFAIDV\PEOPLE\ausername
     Status:   Error
     Message:  Code(-9010) An exception occurred: java.lang.NullPointerException

[05/16/17 16:17:03.345]:IDMREST ST:End transaction.