public function getChildren()
    {
        $children = [];
        $notifications = $this->caldavBackend->getNotificationsForPrincipal($this->principalUri);

        foreach ($notifications as $notification) {
            $children[] = new Node(
                $this->caldavBackend,
                $this->principalUri,
                $notification
            );
        }

        return $children;
    }