Checks whether the string version matches a given version, fix it if not.
Drupal\locale\StringInterface $string: The string object.
string $version: Drupal version to check against.
protected function checkVersion($string, $version) {
  if ($string
    ->getId() && $string
    ->getVersion() != $version) {
    $string
      ->setVersion($version);
    $this->connection
      ->update('locales_source', $this->options)
      ->condition('lid', $string
      ->getId())
      ->fields(array(
      'version' => $version,
    ))
      ->execute();
  }
}