The actual change is in the remoting 1.20.

Full clean Maven build has been failing with PermGen out of space on my system for
a while. Memory analysis indicates that there are excessive javac
instances lying around, so create fresh ones each time to avoid this.

With this change, I no longer need bigger heap size.

Otherwise, eclipse gets unhappy with the @Override annotations.

This is based on watching another person building Jenkins for the first
time.