This can be managed in many ways, like identity immutability, package redirection, and solved from a UI standpoint like "a/foo was moved to b/foo" on your user'

This can be managed in many ways, like identity immutability, package redirection, and solved from a UI standpoint like "a/foo was moved to b/foo" on your user's next package update because the package manager has first-class support for it. Did you think nothing can be improved upon Java?