/**
 * Implements hook_aggregator_fetcher_info_alter().
 */
function {{ machine_name }}_aggregator_fetcher_info_alter(array &$info) {
  if (empty($info['foo_fetcher'])) {
    return;
  }

  $info['foo_fetcher']['class'] = Drupal\foo\Plugin\aggregator\fetcher\FooDefaultFetcher::class;
}