curl -X POST "http://localhost:5001/message" \
  -H "Content-Type: application/json" \
  -d '{
    "message_id": 123456789
  }'

{
  "message_id": 123456789,
  "message_seq": 1001,
  "client_msg_no": "msg_123",
  "from_uid": "user123",
  "channel_id": "group123",
  "channel_type": 2,
  "timestamp": 1640995200,
  "payload": "SGVsbG8gV29ybGQ="
}