@type t() :: %DocuSign.Model.DowngradeBillingPlanInformation{
  downgradeEventType: String.t() | nil,
  planInformation: DocuSign.Model.PlanInformation.t() | nil,
  promoCode: String.t() | nil,
  saleDiscount: String.t() | nil,
  saleDiscountPeriods: String.t() | nil,
  saleDiscountType: String.t() | nil
}