There was a very interesting presentation yesterday at a JUG Lodz meetup by Jakub Nabrdalik showing how to use java's default package scope to create packages that are organized by domain (and not by software layer) and that result in more easily testable, understandable packages. He works at Allegro.pl and while they are big users of Kotlin, he regrets that it lacks package scope.
https://jakubn.gitlab.io/keepitclean/