Jetty12 EE11 preparation

Jakarta EE 11 should be released within a couple of months, thus Jetty will follow with a 12.1.x (https://webtide.com/introducing-jetty-12/). Ideally, this will become a new feature of the Jetty12 bundle.

What are the ideas to support this?

For the light bundle, i can imagine that the EE11 classes can be detected in the classloader, like is done for websocket support. For the main jar, would both EE10 and EE11 servlet classes be part of it? Or would we introduce new classifiers for EE11 servlet? Probably, a new configuration option is needed to specify the EE version to run. 

These imports would be problematic if the EE10 classes are not available, https://github.com/apache/felix-dev/blob/517f9a0c89cad1866f315255568b40c568f5239d/http/jetty12/src/main/java/org/apache/felix/http/jetty/internal/JettyService.java#L34. 

Just wondering how new (or existing 8/9, for that matter) EE specifications would be part of the jetty12 bundle. Of course, we could already try it out with EE9 as an exercise to ease transition to Jetty12.