static Rule fromString(String s) {
            String[] splits = s.split(":");
            return splits.length == 3
                    ? new Rule(splits[0], splits[1], splits[2], Optional.empty())
                    : new Rule(splits[0], splits[1], splits[2], Optional.of(splits[3]));
        }
Only return the projects we'd like to enforce dependencies for: the root project, its modules, their modules, etc.
vespa-enforcer-extensions/src/main/java/com/yahoo/vespa/maven/plugin/enforcer/AllowedDependencies.java