How do I add a namespace reference to a SOAP response with Apache Axis2 and WSDL2Java

<soapenv:Envelope xmlns:soapenv="http://www.w3.org/2003/05/soap-envelope">
   <soapenv:Body>
      <ns1:CreateEntityTypesResponse xmlns:ns1="http://somedomain.com/wsinterface">
         <newKeys>
            <value>1234</value>
         </newKeys>
         <newKeys>
            <value>2345</value>
         </newKeys>
         <newKeys>
            <value>3456</value>
         </newKeys>
         <newKeys xsi:nil="1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"/>
         <newKeys xsi:nil="1" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"/>
         <errors>Error1</errors>
         <errors>Error2</errors>
      </ns1:CreateEntityTypesResponse>
   </soapenv:Body>
</soapenv:Envelope>

// create SOAP envelope with that payload
   org.apache.axiom.soap.SOAPEnvelope env = null;
   env = toEnvelope(
       getFactory(_operationClient.getOptions().getSoapVersionURI()),
       methodName,
       optimizeContent(new javax.xml.namespace.QName
       ("http://tempuri.org/","methodName")));

//adding SOAP soap_headers
_serviceClient.addHeadersToEnvelope(env);

OMNamespace xsi = getFactory(_operationClient.getOptions().getSoapVersionURI()).
    createOMNamespace("http://www.w3.org/2001/XMLSchema-instance", "xsi");

env.declareNamespace(xsi);

SOAPFactory fac = OMAbstractFactory.getSOAP11Factory();
SOAPEnvelope envelope = fac.getDefaultEnvelope();
OMNamespace xsi = fac.createOMNamespace("http://www.w3.org/2001/XMLSchema-instance", "xsi");

envelope.declareNamespace(xsi);
OMNamespace methodNs = fac.createOMNamespace("http://somedomain.com/wsinterface", "ns1");

OMElement method = fac.createOMElement("CreateEntityTypesResponse", methodNs);

//add the newkeys and errors as OMElements here...