API_13.RequestActionFilterAttribute.GetFilterScope C# (CSharp) Метод

        protected FilterScope? GetFilterScope(HttpActionDescriptor descriptor)
        {
            HttpConfiguration configuration = descriptor.Configuration;
            var providers = configuration.Services.GetFilterProviders();
            IEnumerable<FilterInfo> filterInfos;
            FilterInfo result = null;
            foreach (var provider in providers)
            {
                filterInfos = provider.GetFilters(configuration, descriptor);
                result = filterInfos.SingleOrDefault(t => t.Instance == this);
                if (result != null)
                {
                    return result.Scope;
                }

            }

            return null;
        }