如何在slack C#中上传多个附件

using System;
using System.IO;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading.Tasks;

class Program
{
    static async Task Main(string[] args)
    {
        string apiToken = "YOUR_API_TOKEN"; // 您的 Slack API 密钥
        string channel = "CHANNEL_NAME"; // 目标频道的名称或 ID
        string filePath1 = "FILE_PATH_1"; // 第一个附件的文件路径
        string filePath2 = "FILE_PATH_2"; // 第二个附件的文件路径

        using (HttpClient client = new HttpClient())
        {
            client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", apiToken);

            using (MultipartFormDataContent formData = new MultipartFormDataContent())
            {
                // 添加第一个附件
                using (FileStream fileStream = File.OpenRead(filePath1))
                {
                    formData.Add(new StreamContent(fileStream), "file", Path.GetFileName(filePath1));
                }

                // 添加第二个附件
                using (FileStream fileStream = File.OpenRead(filePath2))
                {
                    formData.Add(new StreamContent(fileStream), "file", Path.GetFileName(filePath2));
                }

                // 发送请求
                HttpResponseMessage response = await client.PostAsync($"https://slack.com/api/files.upload?channels={channel}", formData);

                // 处理响应
                string responseBody = await response.Content.ReadAsStringAsync();
                Console.WriteLine(responseBody);
            }
        }
    }
}