private function cleanUpExpiredPreviews() {
        $expiredPreviews=KapostObject::get()->filter('IsKapostPreview', true)->filter('LastEdited:LessThan', date('Y-m-d H:i:s', strtotime('-'.(KapostService::config()->preview_data_expiry).' minutes')));
        if($expiredPreviews->count()>0) {
            foreach($expiredPreviews as $kapostObj) {
                $kapostObj->delete();
            }
        }
    }