code: public String invokeService(Long processId, String ownerType,
              Long ownerId, String masterRequestId, String masterRequest,
              Map<String,String> parameters, String responseVarName, Map<String,String> headers) throws Exception {
          return invokeService(processId, ownerType, ownerId, masterRequestId, masterRequest, parameters, responseVarName, 0, null, null, headers);
      }
docs: Invoke a real-time service process.
  @return the service response