protected function fillSitemap( $sitemap, $root, SearchResult $results )
    {
        foreach ( $results->searchHits as $searchHit )
        {
            /**
             * @var SearchHit $searchHit
             * @var Location  $location
             *
             */
            $location = $searchHit->valueObject;
            $url      = $this->generateUrl( $location, [ ], UrlGeneratorInterface::ABSOLUTE_URL );
            $modified = $location->contentInfo->modificationDate->format( "c" );
            $loc      = $sitemap->createElement( "loc", $url );
            $lastmod  = $sitemap->createElement( "lastmod", $modified );
            $urlElt   = $sitemap->createElement( "url" );
            $urlElt->appendChild( $loc );
            $urlElt->appendChild( $lastmod );
            $root->appendChild( $urlElt );
        }
    }