The release of Jakarta EE poses breaking changes for webapps using Gretty. Hence, discussion in #144 concluded that we require a new major version of Gretty, which then only supports Tomcat 10 and Jetty 10, and dubbed it "Gretty 4" or "Jakarta Gretty".
The milestone's key elements will be removal of non-jakarta servlet containers, adopting of Jakarta, and quite possibly development of new deployment options ("pre-jakarta", "pre-jakarta but JDK 8", "jakarta and JDK 11 onwards").
All related changes will go into branch "gretty4".