/**
  * {@inheritdoc}
  */
 protected function valueForm(&$form, FormStateInterface $form_state)
 {
     parent::valueForm($form, $form_state);
     $form['value'] = array('#type' => 'textfield', '#title' => !$form_state->get('exposed') ? $this->t('Value') : '', '#size' => 30, '#default_value' => $this->value);
 }