public OrderColleague(Mediator mediator, NotifierProxy proxy) : base(mediator, proxy)
 {
 }
 public StockInColleague(Mediator mediator, NotifierProxy proxy) : base(mediator, proxy)
 {
 }
 public Colleague(Mediator mediator, NotifierProxy proxy)
 {
     this.proxy    = proxy;
     this.mediator = mediator;
 }