drupal 8, link validate

HouseForm.php

    $post_codes_base_link = '';
    $post_code_description = $this->house->get('field_postcode')->getDataDefinition()->getDescription();
    if (UrlHelper::isValid($post_code_description, TRUE)) {
      $post_codes_base_url = \Drupal\Core\Url::fromUri($post_code_description);
      $post_codes_base_url->setOptions(['attributes' => ['target' => 'blank']]);
      $post_codes_base_link = \Drupal\Core\Link::fromTextAndUrl(
        t('Lithuania postcodes base'),
        $post_codes_base_url
      );
    }