The checkstyle plugin is intended for use on new files but it is currently disabled. We should enable for as many of our modules as possible.
Arjuna modules should be precluded.
I am not sure if we want to enable it for STM.
Note that we use the WildFly checkstyle rule set (https://github.com/wildfly/wildfly-checkstyle-config/tree/master/src/main/resources/wildfly-checkstyle).