private function getPages()
    {
        $rootPageId = $this->pluginConfig['urlEntries']['pages']['rootPageId'];
        $rootPage = $this->pageRepository->getPage($rootPageId);

        $cacheIdentifier = md5($rootPageId . '-pagesForSitemap');
        if ($this->cacheInstance->has($cacheIdentifier)) {
            $pages = $this->cacheInstance->get($cacheIdentifier);
        } else {
            $pages = $this->getSubPagesRecursive($rootPageId);
            $this->cacheInstance->set($cacheIdentifier, $pages, ['pagesForSitemap']);
        }

        return array_merge([$rootPage], $pages);
    }