Payload of the request to reply on behalf of a contact using their intercom_user_id
A list of files that will be added as attachments.
The time the reply was created. If not provided, the current time will be used.
{ "intercom_user_id": "string", "attachment_files": [ { … } ], "message_type": "comment", "type": "user", "body": "string", "created_at": 1590000000, "attachment_urls": [ "http://example.com" ] }