@FXML
private void onDownloadClicked(ActionEvent downloadClickEvent) {
  // create a task
  geodatabaseSyncTask = new GeodatabaseSyncTask(SERVICE_URL);

  // setup parameters
  GenerateGeodatabaseParameters params = new GenerateGeodatabaseParameters();

  // download features in visible area
  params.setExtent(mapView.getVisibleArea().getExtent());

  // download layer 0
  params.setSyncModel(SyncModel.PER_LAYER);
  params.getLayerOptions().add(new GenerateLayerOption(0));

  // create job, attach listener
  GenerateGeodatabaseJob downloadGeodatabaseJob = geodatabaseSyncTask.generateGeodatabaseAsync(params, geodatabaseFilePath);
  downloadGeodatabaseJob.addJobDoneListener(() -> {
    handleError(downloadGeodatabaseJob.getError());
    progressBar.setVisible(false);
  });

  // execute operation
  progressBar.setVisible(true);
  downloadGeodatabaseJob.start();
}