UpdateSettings.php

<?php

namespace Drupal\update\Plugin\migrate\source;

use Drupal\migrate_drupal\Plugin\migrate\source\Variable;

/**
 * Drupal 6/7 Update settings source from database.
 *
 * For available configuration keys, refer to the parent classes.
 *
 * @see \Drupal\migrate_drupal\Plugin\migrate\source\Variable
 * @see \Drupal\migrate\Plugin\migrate\source\SqlBase
 * @see \Drupal\migrate\Plugin\migrate\source\SourcePluginBase
 *
 * @MigrateSource(
 *   id = "update_settings",
 *   source_module = "update"
 * )
 */
class UpdateSettings extends Variable {
    
    /**
     * {@inheritdoc}
     */
    protected function values() {
        $values = parent::values();
        if (empty($values['update_fetch_url']) || strpos($values['update_fetch_url'], 'http://updates.drupal.org/release-history') !== FALSE) {
            $values['update_fetch_url'] = 'https://updates.drupal.org/release-history';
        }
        return $values;
    }

}