/**
  * Returns the IDs of all child pages of a given $pageID.
  *
  * @param $pageId integer Page ID to start searching
  * @return int[] Child pages
  */
 protected function getChildPages($pageId)
 {
     $children = array();
     $tree = $this->apiWrapper->makePageTreeInstance();
     /** @noinspection PhpUndefinedMethodInspection */
     $tree->init('AND ' . $GLOBALS['BE_USER']->getPagePermsClause(1));
     $tree->makeHTML = FALSE;
     $tree->getTree($pageId, 99, '');
     foreach ($tree->tree as $data) {
         $children[] = intval($data['row']['uid']);
     }
     return $children;
 }