public async ValueTask <IActionResult> PostAsync(User user)
        {
            CreateUserResponse resp = new CreateUserResponse();

            try {
                resp.UserID = await UserBO.CreateUserAsync(user);
            }
            catch (InvalidOperationException inex) {
                return(BadRequest(new ErrorResponse(inex.Message)));
            }
            catch (Exception ex) {
                _logger.LogError(ex.Message);
                return(StatusCode(500, new ErrorResponse(ex.Message)));
            }

            return(Ok(resp.UserID));
        }