/**
     * Creates a new event source and immediately returns it. Creating an event source initiates an
     * asynchronous process to connect the socket. Once that succeeds or fails, `listener` will be
     * notified. The caller must cancel the returned event source when it is no longer in use.
     */
    fun newEventSource(
      request: Request,
      listener: EventSourceListener,
    ): EventSource
  }

   * dependency on those interfaces.
   */
  private class AlpnProvider(
    /** This peer's supported protocols. */
    private val protocols: List<String>,
  ) : InvocationHandler {
    /** Set when remote peer notifies ALPN is unsupported. */
    var unsupported: Boolean = false

    /** The protocol the server selected. */
    var selected: String? = null

    @Throws(Throwable::class)
    override fun invoke(

    /**
     * Creates a new web socket and immediately returns it. Creating a web socket initiates an
     * asynchronous process to connect the socket. Once that succeeds or fails, `listener` will be
     * notified. The caller must either close or cancel the returned web socket when it is no longer
     * in use.
     */
    fun newWebSocket(
      request: Request,
      listener: WebSocketListener,
    ): WebSocket
  }