如何从C#更改IIS中ApplicationPool的用户名/密码？

using System;
using Microsoft.Web.Administration;

public class ChangeAppPoolCredentials
{
    public static void Main()
    {
        using (ServerManager serverManager = new ServerManager())
        {
            // 获取应用程序池
            ApplicationPool appPool = serverManager.ApplicationPools["MyAppPool"];

            // 更改应用程序池的用户名和密码
            appPool.ProcessModel.UserName = "NewUsername";
            appPool.ProcessModel.Password = "NewPassword";
            appPool.ProcessModel.IdentityType = ProcessModelIdentityType.SpecificUser;

            // 提交更改
            serverManager.CommitChanges();
        }
    }
}