public IHttpActionResult PostAdd(Inventory item)
        {
            if (!ModelState.IsValid)
                return BadRequest(ModelState);

            inventoryManagement.Insert(item);
            return Ok();
        }
        public IHttpActionResult PutUpdate(Guid id, Inventory item)
        {
            if (!ModelState.IsValid)
                return BadRequest(ModelState);
            if (id != item.Id)
                return BadRequest();

            IList<ServiceError> errors = inventoryManagement.Update(item);
            return HandleErrors(errors);
        }