LineAudioUserMessage

{
    "data": {
        "channel": 6,
        "chat_user_id": "string",
        "sequence_id": "string",
        "send_time": 0,
        "quote_chat": [],
        "chat_session_id": "string",
        "channel_uid": "string",
        "sys_user_id": 0,
        "msg_type": "audio",
        "msg": {
            "url": "http://example.com",
            "duration": 1
        }
    }
}