Setup Jetty to run with Debugging enabled on port 8000

export MAVEN_OPTS="-Xdebug -Xrunjdwp:transport=dt_socket,server=y,address=8000"

Run Jetty using Maven Plugin

mvn jetty:run

In NetBeans, Goto Debug→ Attach Debugger menu. Select Java Debugger(JPDA) and specify the port as 8000. Now you can debug the webapplication using NetBeans.