Postback message eventThe payload when a user clicks on a postback button.Payload#{ "trigger": "text", "bot_user": { "id": "5e9d6b4712a443e39e69643b7f5ca982", "storage": { "lang": "en" } }, "message": { "id": "814e6c8bdd2f4af1a95645e551feb83b", "postback": "THIS_IS_PAYLOAD_KEY", "received": 1571303978, "language": "en", "message_type": "postback", "source": { "type": "facebook", "raw": { "<RAW_MESSAGE>" } } }}Copy