private function checkProperties()
    {
        if (!isset($this->listId)) {
            throw new \Exception('[listId] is not set', 1);
        }

        if (!isset($this->installationUrl)) {
            throw new \Exception('[installationUrl] is not set', 1);
        }

        if (!isset($this->apiKey)) {
            throw new \Exception('[apiKey] is not set', 1);
        }
    }