Gets the promotion code used to create this Reservation.
The validation of a PromotionCode can be performed by a call of ValidatePromotionCode - Method during reservation-process. But be aware of that's not possible to create a reservation using an invalid PromotionCode, because it's checked by CreateReservation - Method, CreateReservationV2 - Methodand EditReservation - Method.
Reservation Class | SunnyCars.Schema.Osi.WsReservation.V4 Namespace