Optionalpayload?: {The payload of the event. The contents of this object depend on the type of event.
Optionalconversation?: ConversationTruncatedThe conversation linked to the postback.
Optionalpostback?: PostbackWebhookThe postback associated with the event.
Optionalsource?: SourceWithCampaignWebhookThe source of the postback.
Optionaluser?: UserWritableThe user that triggered the postback.
conversation:postback