CSharp: Mediator Pattern in donet core 6

/// <summary>
    /// 中介者模式 Mediator Pattern 亦称： 调解人、控制器、Intermediary、Controller、Mediator
    /// </summary>
    public abstract class User
    {

        /// <summary>
        /// 
        /// </summary>
        protected IGroupChatMediator? _mediator;
        /// <summary>
        /// 
        /// </summary>
        protected string _name;
        /// <summary>
        /// 
        /// </summary>
        /// <param name="name"></param>
        protected User(string name)
        {
            _name = name;
        }
        /// <summary>
        /// 
        /// </summary>
        public string Name => _name;
        /// <summary>
        /// 
        /// </summary>
        /// <param name="mediator"></param>
        public void SetMediator(IGroupChatMediator mediator) => _mediator = mediator;
        /// <summary>
        /// 
        /// </summary>
        /// <param name="message"></param>
        public abstract void Send(string message);
        /// <summary>
        /// 
        /// </summary>
        /// <param name="message"></param>
        public abstract void Receive(string message);

        /// <summary>
        /// 
        /// </summary>
        /// <returns></returns>
        public override string ToString()
        {
            return $"姓名：{Name}";
        }
    }


using Geovin.Du.DuMediator.GroupChat.Components.Common;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml.Linq;

namespace Geovin.Du.DuMediator.GroupChat.Components
{

    /// <summary>
    /// 中介者模式 Mediator Pattern 亦称： 调解人、控制器、Intermediary、Controller、Mediator
    /// </summary>
    public class ViberUser : User
    {
        public ViberUser(string name)
            : base(name)
        {
        }

        public override void Receive(string message) =>
            Console.WriteLine($"{_name} 收到的信息: '{message}'");

        public override void Send(string message)
        {
            if (_mediator == null)
            {
                return;
            }

            Console.WriteLine($"{_name} 发出的信息: '{message}' 给团队");
            _mediator.SendMessage(message, this);
        }
    }
}

    /// <summary>
    /// 中介者模式 Mediator Pattern 亦称： 调解人、控制器、Intermediary、Controller、Mediator
    /// </summary>
    public interface IGroupChatMediator
    {

        /// <summary>
        /// 
        /// </summary>
        /// <param name="user"></param>
        void AddParticipant(User user);
        /// <summary>
        /// 
        /// </summary>
        /// <param name="message"></param>
        /// <param name="sender"></param>
        void SendMessage(string message, User sender);
    }



 /// <summary>
    /// 中介者模式 Mediator Pattern 亦称： 调解人、控制器、Intermediary、Controller、Mediator
    /// </summary>
    public class ViberGroupChatMediator : IGroupChatMediator
    {

        /// <summary>
        /// 
        /// </summary>
        private readonly List<User> _chatParticipants = new();
        /// <summary>
        /// 
        /// </summary>
        /// <param name="users"></param>
        public ViberGroupChatMediator(params User[] users)
        {
            foreach (var user in users)
            {
                AddParticipant(user);
            }

            Console.WriteLine();
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="user"></param>
        public void AddParticipant(User user)
        {
            Console.WriteLine($"{user.Name} 是新的聊天参与者.");

            _chatParticipants.Add(user);
            user.SetMediator(this);
        }
        /// <summary>
        /// 
        /// </summary>
        /// <param name="message"></param>
        /// <param name="sender"></param>
        public void SendMessage(string message, User sender)
        {
            foreach (var user in _chatParticipants.Where(user => user != sender))
            {
                user.Receive(message);
            }
        }
    }

调用：

Geovin.Du.DuMediator.GroupChat.GroupChatExecutor.Execute();

输出：

中介者模式 Mediator Pattern:Group chat demo
--------------------------------------------------
马三 是新的聊天参与者.
张四 是新的聊天参与者.
王五 是新的聊天参与者.

马三 发出的信息: '有人在吗？' 给团队
张四 收到的信息: '有人在吗？'
王五 收到的信息: '有人在吗？'

安琪 是新的聊天参与者.
王五 发出的信息: '我们在.' 给团队
马三 收到的信息: '我们在.'
张四 收到的信息: '我们在.'
安琪 收到的信息: '我们在.'