public function onNavigationItemChildrenRequested(NavigationItem $oNavigationItem) { $mIdentifier = $oNavigationItem->getIdentifier(); if ($oNavigationItem instanceof PageNavigationItem && $oNavigationItem->getMe()->isOfType('journal')) { $this->addChildrenToPageNavigationItem($oNavigationItem); } else { if ($oNavigationItem instanceof VirtualNavigationItem) { $this->addChildrenToVirtualNavigationItem($oNavigationItem); } } }