public async Task <IActionResult> AddGuest([FromRoute] long id, [FromRoute] long guestId)
        {
            if (!ModelState.IsValid)
            {
                return(BadRequest(ModelState));
            }

            var result = await _ReservationService.AddGuestAsync(id, guestId);

            if (!result.Succeeded)
            {
                return(BadRequest(result.Errors));
            }

            return(Ok(result));
        }