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

    private function updateEcho()
    {
        $this->isEcho = !is_null(Helper::array_find($this->_message, 'is_echo'));
        if ($this->isEcho) {
            if (isset($this->message)) {
                $this->message->app_id = Helper::array_find($this->_message, 'app_id');
                $this->message->metadata = Helper::array_find($this->_message, 'metadata');
                $this->message->mid = Helper::array_find($this->_message, 'mid');
                $this->message->seq = Helper::array_find($this->_message, 'seq');
            } else {
                throw new \Exception('Message not yet created for Echo');
            }
        }
    }