code: @Override public final boolean usingProxy() {
      Proxy proxy = route != null
          ? route.getProxy()
          : client.getProxy();
      return proxy != null && proxy.type() != Proxy.Type.DIRECT;
    }
docs: Returns true if either:
  <ul>
  <li>A specific proxy was explicitly configured for this connection.
  <li>The response has already been retrieved, and a proxy was {@link
  java.net.ProxySelector selected} in order to get it.
  </ul>
  
  <p><strong>Warning:</strong> This method may return false before attempting
  to connect and true afterwards.