Christian: Do we replace or update the mapping that's on the message object?
When you create a Message object from a Message object, it replaces the mapping completely, so I'd say we should do the same here, replace the mapping.
Christian: Do we replace or update the mapping that's on the message object?
When you create a Message object from a Message object, it replaces the mapping completely, so I'd say we should do the same here, replace the mapping.