class DefaultFileFormatter

class DefaultFileFormatter extends BaseFieldFileFormatterBase {
  
  /**
   * {@inheritdoc}
   */
  public static function defaultSettings() {
    $settings = parent::defaultSettings();
    $settings['link_to_file'] = TRUE;
    return $settings;
  }
  
  /**
   * {@inheritdoc}
   */
  public function settingsForm(array $form, FormStateInterface $form_state) {
    // We don't call the parent in order to bypass the link to file form.
    return $form;
  }
  
  /**
   * {@inheritdoc}
   */
  protected function viewValue(FieldItemInterface $item) {
    return $item->value;
  }

}