trait DatexWidgetTrait in Datex 8

trait DatexWidgetTrait {
  public static function defaultSettings() {
    return [
      'datex_schema' => 'default',
    ] + parent::defaultSettings();
  }
  public function settingsForm(array $form, FormStateInterface $form_state) {
    $element = parent::settingsForm($form, $form_state);
    $element['datex_schema'] = [
      '#type' => 'select',
      '#title' => t('Date schema'),
      '#default_value' => $this
        ->getSetting('datex_schema'),
      '#options' => _datex_schema_form_options(),
    ];
    return $element;
  }
  public function settingsSummary() {
    $summary = [];
    $summary[] = t('Datex schema: @schema', [
      '@schema' => $this
        ->getSetting('datex_schema'),
    ]);
    return $summary;
  }

}