Nexus-vger is a project mainly written in Java, it's free.
Nexus VaadinGuiEnunciateRemoting Experiment
Here, I use a simple trick to "sneak in" Vaadin based UI for Nexus: create the UI in nexus-vaadin-ui JAR module, and then "stick" (overlay) the two (vaadin ui and the "real" NexusWebapp WAR) and replace web.xml with a modified one. That's it!
Currently the module nexus-remoting-api (Enunciate based REST endpoints) are shut down and unused.
Have fun,
~t~