code: public GetSeveralTracksRequest.Builder getSeveralTracks(String... ids) {
      return new GetSeveralTracksRequest.Builder(accessToken)
              .setDefaults(httpManager, scheme, host, port)
              .ids(concat(ids, ','));
    }
docs: Get multiple tracks.
  
  @param ids The Spotify IDs of all tracks you're trying to retrieve. Maximum: 50 IDs.
  @return A {@link GetSeveralTracksRequest.Builder}.
  @see <a href="https://developer.spotify.com/web-api/user-guide/#spotify-uris-and-ids">Spotify: URLs &amp; IDs</a>