I used to do the same thing, giving total visibility and access inside a package. I do this in my old “Java AI” book (you can get a free copy at https://leanpub.com/javaai by setting the price to free).

I had not touched Java in a long while until yesterday when I wanted to do a quick benchmark of Lucerne to compare it to a search library in another language. I was surprised how easy and quick it was to do this.

I have considered updating my old book for modern Java. It would probably only take a few days to update the examples, but updating the book text would take longer.