return
		}

		var handler *StatelessHandler
		if subID == nil {
			handler = c.handlers.stateless[m.Handler]
		} else {
			handler = c.handlers.subStateless[*subID]
		}
		if handler == nil {
			msg := fmt.Sprintf("Invalid Handler for type: %v", m.Handler)
			if subID != nil {
				msg = fmt.Sprintf("Invalid Handler for type: %v", *subID)
			}
			gridLogIf(ctx, c.queueMsg(m, muxConnectError{Error: msg}))

		}

		m.handlers.single[id] = h
		return nil
	}
	subID := makeSubHandlerID(id, s)
	if m.handlers.hasSubhandler(subID) && !id.isTestHandler() {
		return fmt.Errorf("handler %v, subroute:%v: %w", id.String(), s, ErrHandlerAlreadyExists)
	}
	m.handlers.subSingle[subID] = h
	// Copy so clients can also pick it up for other subpaths.
	m.handlers.subSingle[makeZeroSubHandlerID(id)] = h

        .url(route.address.url)
        .method("CONNECT", null)
        .header("Host", route.address.url.toHostHeader(includeDefaultPort = true))
        .header("Proxy-Connection", "Keep-Alive") // For HTTP/1.0 proxies like Squid.
        .header("User-Agent", USER_AGENT)
        .build()

    val fakeAuthChallengeResponse =
      Response
        .Builder()
        .request(proxyConnectRequest)
        .protocol(Protocol.HTTP_1_1)