UrlAlias.php

<?php

namespace Drupal\path\Plugin\migrate\source\d7;

use Drupal\path\Plugin\migrate\source\UrlAliasBase;

/**
 * Drupal 7 URL aliases source from database.
 *
 * For available configuration keys, refer to the parent classes.
 *
 * @see \Drupal\migrate\Plugin\migrate\source\SqlBase
 * @see \Drupal\migrate\Plugin\migrate\source\SourcePluginBase
 *
 * @MigrateSource(
 *   id = "d7_url_alias",
 *   source_module = "path"
 * )
 */
class UrlAlias extends UrlAliasBase {
    
    /**
     * {@inheritdoc}
     */
    public function fields() {
        $fields = parent::fields();
        $fields['source'] = $this->t('The internal system path.');
        $fields['alias'] = $this->t('The path alias.');
        return $fields;
    }

}