mapdev\FacebookMessenger\Callback\EntryMessage::updatePostback PHP Method

    private function updatePostback()
    {
        $this->isPostback = !is_null(Helper::array_find($this->_message, 'postback'));
        if ($this->isPostback) {
            $this->postback = new Postback(Helper::array_find($this->_message, 'postback'));
        }
    }