public function getNotify()
    {
        if (!empty($this->notify)) {
            return $this->notify;
        }
        try {
            $xml = XML::parse(strval($this->request->getContent()));
        } catch (\Throwable $t) {
            throw new FaultException('Invalid request XML: '.$t->getMessage(), 400);
        } catch (\Exception $e) {
            throw new FaultException('Invalid request XML: '.$e->getMessage(), 400);
        }

        if (!is_array($xml) || empty($xml)) {
            throw new FaultException('Invalid request XML.', 400);
        }

        return $this->notify = new Collection($xml);
    }