@isTest
public class NFMTest_Mock implements WebServiceMock {
   public void doInvoke(
           Object stub,
           Object request,
           Map<String, Object> response,
           String endpoint,
           String soapAction,
           String requestName,
           String responseNS,
           String responseName,
           String responseType) {
       System.debug('aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa');

        // Create response element from the autogenerated class.
       // // Populate response element.
       // // Add response element to the response parameter, as follows:
      OlympusCoJpCommonMessage.Response aa = new OlympusCoJpCommonMessage.Response();
      aa.LOG = new List<OlympusCoJpCommonMessage.LOG_element>();
       //        System.debug('bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb');
       // aa.LOG.add(new OlympusCoJpCommonMessage.LOG_element());
        
       // response = new Map<String,OlympusCoJpCommonMessage.Response>();
       // response.put('response_x', aa); 
       // System.debug(aa);
       //apiEchosign.createEmbeddedWidgetResponse_element respElement = new apiEchosign.createEmbeddedWidgetResponse_element();

       //add all fields you need in the respElement mock response object (it seem you need to populate the "embeddedWidgetCreationResult" member)

       response.put('response_x', aa);

       return;
   }
}