public function revisionPageTitle($openy_upgrade_log_revision) {
    $openy_upgrade_log = $this->entityManager()->getStorage('openy_upgrade_log')->loadRevision($openy_upgrade_log_revision);
    return $this->t('Revision of %title from %date', ['%title' => $openy_upgrade_log->label(), '%date' => format_date($openy_upgrade_log->getRevisionCreationTime())]);
  }