Injection into Servlet not working in Jetty 6.x

Apparently the test suite does not test injection into Servlets for Jetty 6.x because users are reporting that it doesn't work. I added a Servlet injection into the numberguess example and was able to verify that the injection is not taking place, despite receiving the startup message:

INFO: Jetty detected, JSR-299 injection will be available in Servlets and Filters. Injection into Listeners is not supported.

If this turns out to be a user error, then we need to turn to a documentation improvement, because a guy like Antonio should not be having difficulty getting this to work.