BroadcastMessage4ChatroomV21

{
    "create_time": 0,
    "client_broadcast_id": "string",
    "sender_id": "string",
    "from_nick": "string",
    "from_avator": "string",
    "room_id": "string",
    "message_type": 0,
    "text": "string",
    "attachment": {},
    "sender_client_type": 0,
    "high_priority": true,
    "sub_type": 0
}