public async Task <int> GetExtentValues(ModelCode entityType, List <ModelCode> propIds)
        {
            try
            {
                ResourceIterator ri = nm.GetExtentValues(entityType, propIds);
                int retVal          = AddIterator(ri);

                return(retVal);
            }
            catch (Exception ex)
            {
                string message = string.Format("Getting extent values for ModelCode = {0} failed. ", entityType, ex.Message);
                Logger.LogError(message, ex);
                throw new Exception(message);
            }
        }