private synchronized GoogleMusicHttpApi getOrCreateMusicInterface(
      UUID jobId, TokensAndUrlAuthData authData) {

    if (musicHttpApi != null) {
      return musicHttpApi;
    }

    if (musicHttpApisMap.containsKey(jobId)) {
      return musicHttpApisMap.get(jobId);
    }

    GoogleMusicHttpApi newMusicHttpApi = makeMusicHttpApi(authData);
    musicHttpApisMap.put(jobId, newMusicHttpApi);

    return newMusicHttpApi;
  }
Summarizes result as a human-readable string. Empty string indicates no issues.
extensions/data-transfer/portability-data-transfer-google/src/main/java/org/datatransferproject/datatransfer/google/music/GoogleMusicImporter.java