CustomPromotion-Discount.cs

[ContentType(
        DisplayName = "My custom discount",
        GUID = "EDC495FD-8A76-4106-B32E-6EAF9666E170",
        AvailableInEditMode = false)]
    [AvailableContentTypes(Include = new[] { typeof(PromotionData) })]
    public class MyCustomDiscount : EPiServer.Commerce.Marketing.Promotions.BuyQuantityGetItemDiscount
    {
        /// <summary>
        /// The account number for the customer who will apply the promotion
        /// </summary>
        [Display(Name = "Account Number", Order = 10)]
        [PromotionRegion("Condition")]
        [Required]
        [UIHint(UIHint.Textarea)]
        public virtual string AccountNumber { get; set; }
    }