protected function addPageToMountingSiteIndexQueue($mountedPageId, array $mountProperties)
    {
        $siteRepository = GeneralUtility::makeInstance(SiteRepository::class);
        $mountingSite = $siteRepository->getSiteByPageId($mountProperties['mountPageDestination']);

        /** @var $pageInitializer Page */
        $pageInitializer = GeneralUtility::makeInstance(Page::class);
        $pageInitializer->setSite($mountingSite);

        $pageInitializer->initializeMountedPage($mountProperties, $mountedPageId);
    }