The current design of WebSocket interception is coupled to the type of the interceptor.

This type of interception is actually coupled to the binding of the interceptor instead of being part of its nature.

Instead of needing to wrap an interceptor with WebSocketInterceptor and the need of allowApplyToWebSocket we can instead overload HttpProxy#addInterceptor(ProxyInterceptor interceptor) to there declare whether the interceptor applies to WebSocket, e.g. HttpProxy#addInterceptor(ProxyInterceptor interceptor, boolean appliesToWebSocket)

Internally it requires wrapping the interceptor with an object that carries this boolean.