Websocket client creates TCP RST instead proper shutdown on close()

I've first used the Echo Client & Server example [1], but it also happens when the client example is run against an official server like [2].

When close() is called in the client, it leads to:

1. Client: WebSocket Connection Close [FIN]
2. Client: TCP FIN
3. Server: WebSocket Connection Close [FIN]
4. Client: TCP RST

Expected: The websocket as well as the TCP connection are shut down properly.

[1] https://doc.qt.io/qt-5/qtwebsockets-echoserver-example.html
[2] ws://echo.websocket.org