public ActionResult Put([FromBody] UserAchievement changedItem)
        {
            if (changedItem is null)
            {
                return(BadRequest());
            }

            var existingItem = _UserAchievementService.AsQueryable()
                               .Where(x => x.Id == changedItem.Id)
                               .FirstOrDefault();

            if (existingItem is null)
            {
                return(NotFound());
            }

            var item = _UserAchievementService.UpdateUserAchievement(existingItem, changedItem);

            return(Ok(item));
        }