Message
Represents all information about a message in chat. Messages can be either systemic or user generated. There shouldn't be a distinction on the client side about those messages, though you should know they are created in different ways.
As long as you receive this object from whatever source, you have a guarantee that this object exists somewhere on the server. Messages are never generated locally as phantoms.
See also
Inheritors
Types
A list picker displays a list of items, and information about the items, such as product name, description, and image, in the Messages app on the customer's device. The customer can interact multiple times with one or more items from the list. Each interaction should send a reply (on behalf of the user) together with the postback value.
Quick Reply messages have a title to present to the user along with a selection of quick response Action.ReplyButton. The buttons should also be presented to the user, and if the user taps a button, the associated postback should be sent together with the text of the button as a reply message (on behalf of the user). The action can be invoked only once, and the integrating applications have to prevent multiple uses.
Properties
Attachments provided with the message. This field can be empty. It contains attachments that the user or agent sent alongside with the message.
Author associated with this message.
The direction in which the message is sent.
Optional fallback text which can be used if UI integration doesn't support concrete subtype of Message.
The otherwise uncategorizable properties for this message. It can contain anything from message status to custom properties.