How to respond to rename request if user cancelled (via a showMessageRequest)?

I have this scenario:

• User invokes rename
• The location is valid, so prepareRename returns normally
• User enters a name that is already in use (or some other name that would result in invalid code)
• Server sends a showMessageRequest informing the user this will produce an error, with options to "Rename anyway" or "Cancel rename"
• User clicks "Cancel rename"

In this case, if I respond to the original rename request with RequestCancelled, VS Code will show an information notification saying it was cancelled. If I return null, it will show an information notification showing "No result":

So my next thought is to return a WorkspaceEdit that has no changes in it. However, it feels awkward and it's not clear whether this is the correct route.

The spec isn't really clear what a null response means here (nor is it generally clear when clients should/should not show notifications for some responses). This is just one example, but I can imagine many other types of requests could be cancelled by the user via a showMessageRequest, so I think it should be clear how servers should response to requests cancelled in this way (that the client doesn't know were cancelled, because it was server-logic) and how clients should handle that.

Start by reading the specification sections covering rename requests, null results, RequestCancelled, and showMessageRequest responses. Determine how a server-side cancellation should be represented and whether clients should display a notification; done means documenting an unambiguous behavior for this scenario and similar requests.