public async Task <IActionResult> GetImportStatus(string session)
        {
            ImportStateResponse resp = ImportStateService.Get(session); // cache

            if (resp == null)
            {
                FileInformation fileInfo = await _service.GetFileInfo(session); // DB

                if (fileInfo == null)
                {
                    return(NotFound());
                }
                return(Ok(new ImportStateResponse(fileInfo.FinalState)));
            }
            return(Ok(resp));
        }
        public static void SetProgress(string session, ImportState state, int percentage)
        {
            ImportStateResponse resp = new ImportStateResponse(state, percentage);

            sessionMap[session] = resp;
        }
        public static void SetFailed(string session, string description)
        {
            ImportStateResponse resp = new ImportStateResponse(ImportState.Failed, description);

            sessionMap[session] = resp;
        }
        public static void SetReading(string session)
        {
            ImportStateResponse resp = new ImportStateResponse(ImportState.Reading);

            sessionMap[session] = resp;
        }
        public static void SetInitialized(string session)
        {
            ImportStateResponse resp = new ImportStateResponse(ImportState.Initialized);

            sessionMap[session] = resp;
        }