/**
     * Override the [ProxySelector] for the Call.Chain.
     *
     * @throws IllegalStateException if this is a Network Interceptor, since the override is too late.
     */
    fun withProxySelector(proxySelector: ProxySelector): Chain

    /**
     * Returns the proxy [Authenticator] for the OkHttpClient, or an override from the Call.Chain.
     */
    val proxyAuthenticator: Authenticator

    /**