code: function (methodName) {
  
              var smd = this.smd,
                  method = smd.services[methodName],
                  payloadName = (method && method.payload) || smd.payload;
  
              return payloadName;
          }
docs: Returns the name of the primary payload object.
  @param methodName - the service method to return a payload schema for.
  If the "payload" field is not defined on the method, check the service root.