[ModuleDependency(typeof(EPiServer.Commerce.Initialization.InitializationModule))]
public class OrderEventInitialization : IConfigurableModule
{
    public void Initialize(InitializationEngine context)
    {
        OrderContext.Current.OrderGroupUpdated += Current_OrderGroupUpdated;
        OrderContext.Current.OrderGroupDeleted += Current_OrderGroupUpdated;
    }

    private void Current_OrderGroupUpdated(object sender, OrderGroupEventArgs e)
    {
        Task.Run(()=> DoSomething(sender as OrderGroup, e));
    }

    private void DoSomething(OrderGroup order, OrderGroupEventArgs e)
    {
         
    }
}