From instructions provided by Rolf Strijdhorst on the Maven mailing list
In order to stop the jetty server the "Allow termination of remote VM" should be checked in debug dialog in Step 2. When you have the jetty server running and the debugger connected you can switch to the debug perspective. In the debug view, right click on the Java HotSpot(TM) Client VM[localhost:4000] and chose terminate. This will stop the debugger and the jetty server.