如何在Polly重试中更改HttpMessageHandler的配置？

using System;
using System.Net.Http;
using Polly;
using Polly.Retry;

public class CustomHttpMessageHandler : DelegatingHandler
{
    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        // 在每次请求之前更改Http请求的配置
        request.Headers.Add("CustomHeader", "CustomValue");
        
        // 调用基类的SendAsync方法发送请求
        var response = await base.SendAsync(request, cancellationToken);
        
        return response;
    }
}

public class Program
{
    public static void Main()
    {
        // 创建自定义的HttpMessageHandler
        var customHandler = new CustomHttpMessageHandler();
        
        // 创建HttpClient，并将自定义的HttpMessageHandler传递给它
        var httpClient = new HttpClient(customHandler);
        
        // 创建重试策略
        var retryPolicy = Policy
            .Handle<HttpRequestException>()
            .RetryAsync(3, (exception, retryCount) =>
            {
                // 在每次重试之前执行的逻辑
                Console.WriteLine($"Retrying request. Retry count: {retryCount}");
            });
        
        // 使用重试策略发送HTTP请求
        var response = await retryPolicy.ExecuteAsync(() => httpClient.GetAsync("https://example.com"));
        
        // 处理响应
        if (response.IsSuccessStatusCode)
        {
            // 处理成功的响应
        }
        else
        {
            // 处理失败的响应
        }
    }
}