When we are ready to deliver EE 9, create a PR to merge the compatibility branch of https://github.com/basil/javax-servlet-api into the default branch of https://github.com/jenkinsci/javax-servlet-api. This PR should add functionality to bridge to/from EE 8/9 in both directions. Once it has been released, update the jakarta branch of Stapler and the forward branch of Jenkins test harness with the new release.