Note that getTraits will NOT return any traits inherited from a parent.
This is currently viewed as the desired behavior. See https://bugs.php.net/bug.php?id=61554
(PHP 5 >= 5.4.0, PHP 7)
ReflectionClass::getTraits — 返回这个类所使用的 traits 数组
本函数还未编写文档，仅有参数列表。
此函数没有参数。
返回了一个数组，键是 trait 的名称，值是 trait 实例的 ReflectionClass。
出现错误的情况下返回 NULL。
Note that getTraits will NOT return any traits inherited from a parent.
This is currently viewed as the desired behavior. See https://bugs.php.net/bug.php?id=61554