private void checkBack() {
        if (levelControllerRepo != null) {
            Enumeration<String> e = LogManager.getLogManager().getLoggerNames();
            while (e.hasMoreElements()) {
                String name = e.nextElement();
                LevelController ctrl = getLevelControl(name);
                ctrl.checkBack();
            }
            levelControllerRepo.checkBack();
        }
    }
level controller for default levels (first-time logging
or logging without a logcontrol file)
vespalog/src/main/java/com/yahoo/log/VespaLevelControllerRepo.java