请问restlet客户端如何设置代理

HttpClient4.3.6 中可以如下设置代理：

CloseableHttpClient httpClient = null;
HttpHost proxy = new HttpHost(proxyHost, proxyPort);
DefaultProxyRoutePlanner routePlanner = new DefaultProxyRoutePlanner(proxy);
httpClient = HttpClients.custom().setRoutePlanner(routePlanner).build();

restlet框架中，客户端请求中如何设置代理？