public IActionResult Index(string conventionId)
        {
            var viewModel = new ConventionStatisticsViewModel();

            if (conventionId.IsEmptyString() && Actor.HasManagedConvention)
            {
                conventionId = Actor.ManagedConvention.ConventionId;
            }

            if (conventionId.IsEmptyString())
            {
                return(View(viewModel));
            }

            viewModel = Gateway.BuildStatisticView(conventionId);
            return(View(viewModel));
        }