docs: private static void verifyJUnit4Present() {
      try {
        Class<?> clazz = Class.forName("org.junit.runner.Description");
        if (!Serializable.class.isAssignableFrom(clazz)) {
          JvmExit.halt(SlaveMain.ERR_OLD_JUNIT);
        }
      } catch (ClassNotFoundException e) {
        JvmExit.halt(SlaveMain.ERR_NO_JUNIT);
      }
    }