mapdev\FacebookMessenger\Messages\AttachmentMessage::toArray PHP Method

    public function toArray()
    {
        $this->checkRecipient();
        if (is_null($this->attachment_type)) {
            throw CouldNotCreateMessage::noAttachmentType();
        }
        if (is_null($this->attachment_url) && is_null($this->attachment_id)) {
            throw CouldNotCreateMessage::noAttachmentUrl();
        }
        $payload = ['url' => $this->attachment_url];
        if ($this->is_reuseable) {
            $payload['is_reuseable'] = true;
        }
        if (!is_null($this->attachment_id)) {
            $payload = ['attachment_id' => $this->attachment_id];
        }
        return ['recipient' => ['id' => $this->recipient_id], 'message' => ['attachment' => ['type' => $this->attachment_type, 'payload' => $payload]]];
    }