protected synchronized  AppleMusicInterface makeMusicInterface(
          TokensAndUrlAuthData authData,
          AppCredentials appCredentials,
          String exportingService,
          Monitor monitor) {

    Preconditions.checkNotNull(authData, ERROR_MESSAGE, "authData");
    Preconditions.checkNotNull(appCredentials, ERROR_MESSAGE, "appCredentials");
    Preconditions.checkNotNull(exportingService, ERROR_MESSAGE, "exportingService");
    Preconditions.checkNotNull(monitor, ERROR_MESSAGE, "monitor");

    return new AppleMusicInterface(authData, appCredentials, exportingService, monitor);
  }
The Factory class that creates the Apple Import Extensions.
extensions/data-transfer/portability-data-transfer-apple/src/main/java/org/datatransferproject/datatransfer/apple/AppleInterfaceFactory.java