Apache Commons Digester library removal (breaking changes!)
Keeping up with our goal to clean up some of the technical debt inside Jenkins Core and reduce the maintenance overheads, we are happy to report we were able to remove a long-deprecated Apache Commons Digester library.
Jenkins Core does not depend anymore on Apache Commons Digester v.2.1, a version that has been released in 2010.
Some plugins will require update to operate properly after the Jenkins core upgrade. See JEP-231 for the full list of the affected plugins. Below there is the list of plugins that did not have their fix released at the time of writing. They will start to break with the weekly on the 7th of June, expected to be the 2.297.
In addition to these still-served plugins, a few others will break.
Note however that these were already suspended  for various reasons, so we do recommend to move away from using them or step up as maintainers.
The IDs for these plugins are:
It is always a good idea to update all your plugins before upgrading Jenkins core.
Please reach out on the developers’ list with any questions or suggestions.
Getting fixes in the affected plugins
For all affected plugins we have submitted pull requests with compatibility patches. These plugins seem to have no active maintainer, and hence we cannot commit on delivering those fixes. In mean time you can build a custom patch locally to resolve the issue on your instances. If you use any of those plugins, consider stepping up and adopting them so that the fixes could be released. We will appreciate any contributions!