public Task <IEnumerable <ValidationResult> > ValidateSettingsAsync(FacebookLoginSettings settings)
        {
            if (settings == null)
            {
                throw new ArgumentNullException(nameof(settings));
            }

            var results = ImmutableArray.CreateBuilder <ValidationResult>();

            return(Task.FromResult <IEnumerable <ValidationResult> >(results));
        }
        public async Task UpdateSettingsAsync(FacebookLoginSettings settings)
        {
            if (settings == null)
            {
                throw new ArgumentNullException(nameof(settings));
            }
            var container = await _siteService.GetSiteSettingsAsync();

            container.Properties[nameof(FacebookLoginSettings)] = JObject.FromObject(settings);
            await _siteService.UpdateSiteSettingsAsync(container);
        }