When we are ready to deliver EE 9, create a PR to merge the jakarta branch of jenkinsci/jelly into the default branch. This PR should update the versions of jakarta.servlet:jakarta.servlet-api and jakarta.servlet.jsp.jstl:jakarta.servlet.jsp.jstl-api to EE 9 versions as well as replacing all javax imports with jakarta imports. Once it has been released, update the jakarta branches of Stapler and Jenkins core with the new release.