The message's data (or payload)
Optional headersPossible headers that may have been set by the server or the publisher.
Optional replyA possible subject where the recipient may publish a reply (in the cases where the message represents a request).
The subscription ID where the message was dispatched.
The subject the message was sent to
Convenience to publish a response to the reply subject in the
message - this is the same as doing nc.publish(msg.reply, ...).
Optional payload: PayloadOptional opts: PublishOptions
Represents a message delivered by NATS. This interface is used by Subscribers.