code: public static void setReflect(Config conf, Class<? extends KryoInstantiator> instClass) {
      conf.set(KEY, instClass.getName());
    }
docs: In this mode, we are just refecting to another delegated class. This is preferred
  if you don't have any configuration to do at runtime (i.e. you can make a named class
  that has all the logic for your KryoInstantiator).