Following the Checkstyle lead, Checkstyle Addons has also moved to Java 8 (hence the new major version).
Plus, the propertyFile option of the PropertyCatalog check
features a new placeholder.
Starting with Checkstyle 7.0, Checkstyle requires Java 8. So, Checkstyle Addons is now also compiled
for Java 8 by default. If you are on a previous Java version, that’s fine! You may use the artifacts
postfixed with java7 or java6, respectively. They are functionally equivalent, but work with previous
levels of Java and the corresponding older versions of Checkstyle.