@type t() :: %PolarExpress.Schemas.Checkout{
  active_trial_interval: PolarExpress.Schemas.TrialInterval.t() | nil,
  active_trial_interval_count: integer() | nil,
  allow_discount_codes: boolean() | nil,
  allow_trial: boolean() | nil,
  amount: integer() | nil,
  attached_custom_fields: [PolarExpress.Schemas.AttachedCustomField.t()] | nil,
  billing_address_fields:
    PolarExpress.Schemas.CheckoutBillingAddressFields.t() | nil,
  client_secret: String.t() | nil,
  created_at: DateTime.t() | nil,
  currency: String.t() | nil,
  custom_field_data:
    %{
      required(String.t()) =>
        String.t() | integer() | boolean() | DateTime.t() | nil
    }
    | nil,
  customer_billing_address: PolarExpress.Schemas.Address.t() | nil,
  customer_billing_name: String.t() | nil,
  customer_email: String.t() | nil,
  customer_external_id: String.t() | nil,
  customer_id: String.t() | nil,
  customer_ip_address: String.t() | nil,
  customer_metadata:
    %{required(String.t()) => String.t() | integer() | boolean() | nil} | nil,
  customer_name: String.t() | nil,
  customer_tax_id: String.t() | nil,
  discount:
    PolarExpress.Schemas.CheckoutDiscountFixedOnceForeverDuration.t()
    | PolarExpress.Schemas.CheckoutDiscountFixedRepeatDuration.t()
    | PolarExpress.Schemas.CheckoutDiscountPercentageOnceForeverDuration.t()
    | PolarExpress.Schemas.CheckoutDiscountPercentageRepeatDuration.t()
    | nil,
  discount_amount: integer() | nil,
  discount_id: String.t() | nil,
  embed_origin: String.t() | nil,
  expires_at: DateTime.t() | nil,
  external_customer_id: String.t() | nil,
  id: String.t() | nil,
  is_business_customer: boolean() | nil,
  is_discount_applicable: boolean() | nil,
  is_free_product_price: boolean() | nil,
  is_payment_form_required: boolean() | nil,
  is_payment_required: boolean() | nil,
  is_payment_setup_required: boolean() | nil,
  locale: String.t() | nil,
  metadata: PolarExpress.Schemas.MetadataOutputType.t() | nil,
  modified_at: DateTime.t() | nil,
  net_amount: integer() | nil,
  organization_id: String.t() | nil,
  payment_processor: PolarExpress.Schemas.PaymentProcessor.t() | nil,
  payment_processor_metadata: %{required(String.t()) => String.t()} | nil,
  price_per_seat: integer() | nil,
  prices:
    %{
      required(String.t()) => [
        PolarExpress.Schemas.LegacyRecurringProductPrice.t()
        | PolarExpress.Schemas.ProductPrice.t()
        | nil
      ]
    }
    | nil,
  product: PolarExpress.Schemas.CheckoutProduct.t() | nil,
  product_id: String.t() | nil,
  product_price:
    PolarExpress.Schemas.LegacyRecurringProductPrice.t()
    | PolarExpress.Schemas.ProductPrice.t()
    | nil,
  product_price_id: String.t() | nil,
  products: [PolarExpress.Schemas.CheckoutProduct.t()] | nil,
  require_billing_address: boolean() | nil,
  return_url: String.t() | nil,
  seats: integer() | nil,
  status: PolarExpress.Schemas.CheckoutStatus.t() | nil,
  subscription_id: String.t() | nil,
  success_url: String.t() | nil,
  tax_amount: integer() | nil,
  total_amount: integer() | nil,
  trial_end: DateTime.t() | nil,
  trial_interval: PolarExpress.Schemas.TrialInterval.t() | nil,
  trial_interval_count: integer() | nil,
  url: String.t() | nil
}