/**
 * Implements hook_system_info_alter().
 */
function {{ machine_name }}_system_info_alter(array &$info, \Drupal\Core\Extension\Extension $file, $type) {
  // Only fill this in if the .info.yml file does not define a 'datestamp'.
  if (empty($info['datestamp'])) {
    $info['datestamp'] = $file->getMTime();
  }
}