public IHttpActionResult GetGPExportFile(int selectionId, int depositId)
        {
            return(Authorized(token =>
            {
                try
                {
                    // get export file and name
                    var deposit = _gatewayDonationService.GetDepositById(depositId);
                    var fileName = _gatewayDonationService.GPExportFileName(deposit);
                    var stream = _gatewayDonationService.CreateGPExport(selectionId, depositId, token);

                    return new FileResult(stream, fileName);
                }
                catch (Exception ex)
                {
                    var apiError = new ApiErrorDto("GP Export File Creation Failed", ex);
                    throw new HttpResponseException(apiError.HttpResponseMessage);
                }
            }));
        }