As far as I am aware, there is no mechanism built into RTC to do that out of the box.

The general approach could be to compare the repository workspace with the stream. This would provide you with the differences. This could be done using the SCM Commandline (search for lscm or scm in the documentation), or programmatically using the Java API (which might be not trivial).

Having said that, this would only be possible if the repository workspaces of the users are visible to the public or scoped and the user that runs the compare is in that scope.

If the repository workspace is private, I don't think it could be accessed (except changing ownership using an admin account and changing visibility).

I personally think that this would be a waste of time, resources and performance of the server. There is a good reason, why the repository workspace is owned by the users and why the developer has to decide when to deliver.