Reproduced steps:
1. obtain a WebSocket connection
2. send or receive some message, but make sure let at least 1 message from server not handled.
You can achieve this by invoking WebSocket.request(long n) method with a value less than total message expected or just not invoke this method.
3. client side send close
(or initialize the closing handshake from server side)
4. check state with WebSocket.isClosed() immediately. It will return false.
5. even when we wait for more than 60 seconds to let the underlying connection closes, WebSocket.isClosed() still return false!

I also attached a simple test to indicate the problem