docs: @Override public WebViewMapFragment build() {
      if (options == null) {
        options = new GoogleWebMapType();
      }
      if (options instanceof GoogleWebMapType) {
        return GoogleWebViewMapFragment.newInstance(options);
      }
      if (options instanceof GoogleChinaMapType) {
        return GoogleChinaWebViewMapFragment.newInstance(options);
      }
      if (options instanceof LeafletMapType) {
        return LeafletWebViewMapFragment.newInstance(options);
      }
      return null;
    }