说明：  lua仿jdk8.0的Optional工具类， 在判断objcet为空时可以不用 if obj== nil 这种粗暴的写法了。 使用Optional可以优雅的简洁的进行非空判断 用法：Optional.of(obj, function() end)
(Lua jdk8.0 like Optional tool class, in the judgment objcet is empty, you can not use if obj== nil this rude writing. Optional can be used gracefully and concisely for non-empty judgment: Optional. of (obj, function () end))