private synchronized GoogleMusicHttpApi makeMusicHttpApi(TokensAndUrlAuthData authData) {
    Credential credential = credentialFactory.createCredential(authData);
    return new GoogleMusicHttpApi(
        credential, jsonFactory, monitor, credentialFactory, writesPerSecond);
  }
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