/// <inheritdoc/>
        public async Task <IEnumerable <Models.PlaylistItem> > GetPlaylistItems(string id)
        {
            var playlistItems = m_YouTubeService !.PlaylistItems.List("snippet");

            // 100件まで編集可能とする
            playlistItems.MaxResults = 100;
            playlistItems.PlaylistId = id;

            var items = await playlistItems.ExecuteAsync();

            var resultPlaylistItems = new List <Models.PlaylistItem>();

            foreach (var playlistItem in items.Items)
            {
                try
                {
                    if (playlistItem.Snippet.Thumbnails.Default__ == null)
                    {
                        resultPlaylistItems.Add(new Models.PlaylistItem(playlistItem.Id, playlistItem.Snippet.ResourceId, playlistItem.Snippet.Title, playlistItem.Snippet.Description, string.Empty));
                    }
                    else
                    {
                        resultPlaylistItems.Add(new Models.PlaylistItem(playlistItem.Id, playlistItem.Snippet.ResourceId, playlistItem.Snippet.Title, playlistItem.Snippet.Description, playlistItem.Snippet.Thumbnails.Default__.Url));
                    }
                }
                catch
                {
                    // エラーが発生した場合は何もしない
                }
            }

            return(resultPlaylistItems);
        }
        public async Task <List <PlaylistItem> > GetPlaylistItems(string playlistId)
        {
            // https://developers.google.com/youtube/v3/docs/playlistItems/list
            var playlistItems = PlaylistItems.List("contentDetails,id,snippet,status");

            playlistItems.PlaylistId = playlistId;
            return(await HandlePagination <PlaylistItem>(playlistItems));
        }