public String getMainComponentName() {
    return mMainComponentName;
}

protected void onCreate(Bundle savedInstanceState) {
    String mainComponentName = getMainComponentName();
    mReactDelegate =
        new ReactDelegate(
            getPlainActivity(), getReactNativeHost(), mainComponentName, getLaunchOptions()) {
          @Override
          protected ReactRootView createRootView() {
            return ReactActivityDelegate.this.createRootView();
          }
        };
    // mMainComponentName rename is mainComponentName 
    if (mainComponentName != null) {
      loadApp(mainComponentName);
    }
  }