Francis Labrie as far as I can tell, there is no active development being done on the xcode plugin. I used the instructions from the DevOps World 2021 "Contributing to Open Source" workshop and made a few modernization improvements to the plugin in PR-112. I confirmed that the automated tests in the plugin repository all pass after my changes. I confirmed that I can build and test with Java 11.
I do not have access to a macOS machine or an XCode development environment, so I have no way of knowing if the updates work when installed by a user.
If you would like to try my changes, you could download the build from https://ci.jenkins.io/job/Plugins/job/xcode-plugin/job/PR-112/ and install it on your system. If it works, please provide feedback on PR-112.
If the plugin is crucial to your work, you may want to ask your employer to support your work efforts by allowing you to adopt the plugin.