This is a technical release which was required in order to retain compatibility with Checkstyle 6.15.
The folks at Checkstyle have added a check called RegexpOnFilename, which happens to be heavily inspired by our own check of the same name. So, to avoid name collisions, we had to rename our original check.
To migrate to Checkstyle Addons 2.0.0, simply rename RegexpOnFilename to RegexpOnFilenameOrg in your config file. If you are still on Checkstyle 6.14.1 or earlier, you do not need to upgrade Checkstyle Addons.