As a modern java developer I was surprised to find no mention of Vert.X which to me seems like one of the most modern and forward-thinking java web frameworks. Not only does it support scaling your app out-of-the-box but also provides a simple way to deal with concurrency.
The title did warn that it is an opinionated guide.
I think most projects that used Maven before Gradle don't have enough incentive to migrate. A lot of the new projects, however, start out with gradle: Vert.x, Crate.io, RxJava.