In 2.0, we've included a Setup Wizard and an Upgrade Wizard, both which need to have information about how the instance was upgraded. These store the last run/update version, which may prove to be insufficient to determine the upgrade path for a Jenkins instance.

To aid this, we could modify the InstallUtil version to be more of an update log instead of only containing the last version, using a JSON format or something similar. We could use that to track all version upgrades, downgrades, and attach timestamps and metadata to each version, so things like this we could fairly easily use to display upgrade wizards at version 2.0, 2.1, etc., and it would consolidate these related features together and may be able to provide more information to support any issues that arise.