public Error insertTracksInPlaylist(long playlist, Collection<Long> tracks)
      throws IOException {
    if (tracks.isEmpty()) {
      return null;
    }
    // Track inserts return true if successful and an Error json object on error....
    String result = makePostRequest(
        BASE_URL + "/playlist/" + playlist + "/tracks",
        ImmutableMap.of("songs", Joiner.on(",").join(tracks)));
    if ("true".equalsIgnoreCase(result)) {
      return null;
    }
    return MAPPER.readValue(result, Error.class);
  }
A utility wrapper for interacting with the Deezer Api.

<p>See: https://developers.deezer.com/api/explorer
extensions/data-transfer/portability-data-transfer-deezer/src/main/java/org/datatransferproject/transfer/deezer/DeezerApi.java