1. The pre-build step that fetches dependency should simply use the `dependency:resolve` goal. This will avoid the execution of checkstyle, which then will be done in the actual build step (not the "intstall" step). And hopefully, then we'll get detailed logs about what checkstyle rules failed (since the actual build is not executed in silent mode).
2. The "install" goal should only be executed on the build-config project (to install checkstyle rules)
3. We should exclude the artifacts installed as part of our builds from the cache
4. Upgrade to a more recent version of ubuntu?
5. Maybe use OpenJDK instead of OracleJDK? I've heard from Remi Forax (OpenJDK developper) that there's almost no difference between the two in JDK8 (only font rendering), and none at all starting from JDK9. That's because Oracle sells their additions instead of including them in their general public JDK.