@type t() :: %PolarExpress.Schemas.CheckoutLink{
  allow_discount_codes: boolean() | nil,
  client_secret: String.t() | nil,
  created_at: DateTime.t() | nil,
  discount:
    PolarExpress.Schemas.DiscountFixedOnceForeverDurationBase.t()
    | PolarExpress.Schemas.DiscountFixedRepeatDurationBase.t()
    | PolarExpress.Schemas.DiscountPercentageOnceForeverDurationBase.t()
    | PolarExpress.Schemas.DiscountPercentageRepeatDurationBase.t()
    | nil,
  discount_id: String.t() | nil,
  id: String.t() | nil,
  label: String.t() | nil,
  metadata: PolarExpress.Schemas.MetadataOutputType.t() | nil,
  modified_at: DateTime.t() | nil,
  organization_id: String.t() | nil,
  payment_processor: PolarExpress.Schemas.PaymentProcessor.t() | nil,
  products: [PolarExpress.Schemas.CheckoutLinkProduct.t()] | nil,
  require_billing_address: boolean() | nil,
  return_url: String.t() | nil,
  success_url: String.t() | nil,
  trial_interval: PolarExpress.Schemas.TrialInterval.t() | nil,
  trial_interval_count: integer() | nil,
  url: String.t() | nil
}