Mediator Design Patterns (Behavioral Patterns) in C#

*Define an object that encapsulates how a set of objects interact. 
     ** Mediator promotes loose coupling by keeping objects from referring to each other explicitly, 
     * it lets you vary their interaction independently.

class Program
    {
        static void Main(string[] args)
        {
            ConcreteMediator m = new ConcreteMediator();

            ConcreteColleague1 c1 = new ConcreteColleague1(m);
            ConcreteColleague2 c2 = new ConcreteColleague2(m);

            m.Collegue1 = c1;
            m.Collegue2 = c2;

            c1.Send("How are you");
            c2.Send("Fine, Thanks");

            Console.ReadKey();
        }
    }

    abstract class Mediator
    {
        public abstract void Send(string message, Colleague colleague);
    }
    abstract class Colleague
    {
        protected Mediator mediator;
        public Colleague(Mediator mediator)
        {
            this.mediator = mediator;
        }
    }
    class ConcreteColleague1 : Colleague
    {
        public ConcreteColleague1(Mediator mediator) : base(mediator) { }
        public void Send(string message)
        {
            mediator.Send(message, this);
        }
        public void Notify(string message)
        {
            Console.WriteLine("Colleague 1 get message" + message);
        }
    }
    class ConcreteColleague2 : Colleague
    {
        public ConcreteColleague2(Mediator mediator) : base(mediator) { }
        public void Send(string message)
        {
            mediator.Send(message, this);
        }
        public void Notify(string message)
        {
            Console.WriteLine("Colleague 2 get message" + message);
        }
    }
    
    class ConcreteMediator : Mediator
    {
        private ConcreteColleague1 _collegue1;
        private ConcreteColleague2 _collegue2;

        internal ConcreteColleague1 Collegue1
        {
            set { _collegue1 = value; }
        }       

        internal ConcreteColleague2 Collegue2
        {
            set { _collegue2 = value; }
        }

        public override void Send(string message, Colleague colleague)
        {
            if (colleague == _collegue1)
                _collegue2.Notify(message);
            else
                _collegue1.Notify(message);
        }
    }