{
  "token": "verification-token-not-a-secret",
  "team_id": "TDEMO",
  "api_app_id": "ADEMO",
  "event_id": "Ev_MPIM_TOP_001",
  "event_time": 1782770430,
  "type": "event_callback",
  "event": {
    "type": "message",
    "channel": "C_GROUP_DM",
    "user": "U_ALICE",
    "text": "group DM chatter",
    "ts": "1782770430.000400",
    "event_ts": "1782770430.000400",
    "channel_type": "mpim"
  }
}