Outdated doc for Websockets

Play Version (2.5.4)

API (Scala)

Operating System (MacOS 10.11)

Hello, I try to get familiar with WebSockets in Play. I am following https://www.playframework.com/documentation/2.5.x/ScalaWebSockets#closing-a-websocket. After a few hours wasted I found out that this doc is probably outdated. In current Play you close Websocket connection by closing underlying akka-stream. Would be great if you can update docs accordingly.

Probably you don't need a reproducer because I feel it's expected behavior, but just in case:

Expected Behavior

1. after sending PoisonPill connection is getting closed

Actual Behavior

after sending PoisonPill connection is not getting closed. I base that on:

1. my client's callback onclose is not fired,
2. Chrome's network Tab shows WS connection as Pending

Reproducible Test Case

you can see this code at https://github.com/note/play-ws-example, here's what is essential for this case: https://github.com/note/play-ws-example/blob/master/app/controllers/WebSocketController.scala. I also included my JS code here: https://github.com/note/play-ws-example/tree/master/client

Start with the Scala WebSockets documentation at the linked closing-a-websocket section and compare its guidance with app/controllers/WebSocketController.scala in the linked example. Check the client code and browser behavior described in the issue, then update the documentation to match the current connection-closing behavior and confirm the example's WebSocket closes as expected.