Searching for an implementation of the Web Push API

I’m implementing a notifications system and I was wondering if anybody has a sample implementation of the Web Push protocol, see:

I could find an implementation for Node.js, see web-push, was wondering if something similar exists that could be used with Play or Akka-HTTP.

Eventually found the webpush-java library. Apparently I misunderstood what the library does, so this isn’t related to HTTP servers.