如何在csom上下文中获取retry after报头？

using Microsoft.SharePoint.Client;
using System;
using System.Net;

class Program
{
    static void Main(string[] args)
    {
        string siteUrl = "https://your-sharepoint-site-url";
        string listTitle = "Your List Title";

        using (ClientContext context = new ClientContext(siteUrl))
        {
            // 发送HTTP请求并获取响应
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(siteUrl);
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();

            // 获取Retry-After报头的值
            string retryAfterValue = response.Headers["Retry-After"];

            Console.WriteLine("Retry-After报头的值为：" + retryAfterValue);
        }
    }
}