A HandshakeInterceptor can be used to intercept WebSocket handshakes
(or SockJS requests where a new session is created) in order to
inspect the request and response before and after the handshake
including the ability to pass attributes to the WebSocketHandler,
which the hander can access through
WebSocketSession.getHandshakeAttributes()
An HttpSessionHandshakeInterceptor is available that can copy
attributes from the HTTP session to make them available to the
WebSocket session.
Issue: SPR-10624
319f18dddf