outgoingMessage.pipe()

重写了继承自旧版 Stream 类的 stream.pipe() 方法，而 Stream 是 http.OutgoingMessage 的父类。

【Overrides the stream.pipe() method inherited from the legacy Stream class which is the parent class of http.OutgoingMessage.】

调用此方法会抛出 Error，因为 outgoingMessage 是一个只写流。

【Calling this method will throw an Error because outgoingMessage is a write-only stream.】