Building Java applications using Undertow with a build setup in gradle is not _that_ different from a node.js service using Express and package.json for dependencies, or a Ruby, Sinatra and Rake stack. After having tried all three, I ended up going back to the JVM. It's not a perfect ecosystem, but it's damned good one.
Also there's definitely been some cross pollination of ideas from at least the Ruby world to the Java (Rails inspiring Grails and probably Play too), so it's getting better. Add java8 lambdas, and it's quite nice.
Aren't you optimistic.
https://github.com/search?l=Maven+POM&q=pom.xml&type=Code&ut...
https://github.com/search?l=Gradle&q=build.gradle&type=Code&...
And that's public github, which is supposed to be more cutting edge than the legacy code that powers most companies. I started a project with gradle on my last team and everyone complained because they had never used it before.