'continue' 事件

当服务器发送 '100 Continue' HTTP 响应时触发，通常是因为请求包含 'Expect: 100-continue'。 这是客户端应该发送请求正文的指令。

Emitted when the server sends a '100 Continue' HTTP response, usually because the request contained 'Expect: 100-continue'. This is an instruction that the client should send the request body.