public async Task <IActionResult> History(int?userId)
        {
            if (!Project.ExplicitSubmissionRequired)
            {
                return(NotFound());
            }

            if (userId == null)
            {
                userId = User.Id;
            }

            if (userId != User.Id && ClassroomRole < ClassroomRole.Admin)
            {
                return(Forbid());
            }

            var builds = await BuildService.GetUserBuildsAsync
                         (
                ClassroomName,
                ProjectName,
                userId.Value
                         );

            if (builds.Count == 0)
            {
                return(NotFound());
            }

            var viewModel = new HistoryViewModel(builds.First().Commit.User, builds);

            return(View(viewModel));
        }