Flink:RichAsyncFunction 中的有状态访问?

Flink: stateful access in RichAsyncFunction?

Flink documentation for RichAsyncFunction 声明:

State related apis in RuntimeContext are not supported yet because the key may get changed while accessing states in the working thread.

这到底是什么意思?哪些呼叫是允许的,哪些是不允许的?如果调用不受支持的方法会发生什么?

RuntimeContext 的文档是 here

RichAsyncFunction 提供了它自己的 RuntimeContext 子类,它在尝试访问任何状态时抛出 UnsupportedOperationException