public async Task <IActionResult> UnassignUserAchievement(int userId, int achievementId)
        {
            var result = await _userAchievementService.UnassignUserAchievementAsync(userId, achievementId);

            if (!result.Success)
            {
                return(BadRequest(result.Message));
            }
            var achievementResource = _mapper.Map <Achievement, AchievementResource>(result.Resource.Achievement);

            return(Ok(achievementResource));
        }