public async Task <int> GetRelatedValues(long source, List <ModelCode> propIds, Association association)
        {
            try
            {
                ResourceIterator ri = nm.GetRelatedValues(source, propIds, association);
                int retVal          = AddIterator(ri);

                return(retVal);
            }
            catch (Exception ex)
            {
                string message = string.Format("Getting related values for resource with ID = 0x{0:x16} failed. {1}", source, ex.Message);
                Logger.LogError(message, ex);
                throw new Exception(message);
            }
        }