@type t() :: %PolarExpress.Schemas.Subscription{
  amount: integer() | nil,
  cancel_at_period_end: boolean() | nil,
  canceled_at: DateTime.t() | nil,
  checkout_id: String.t() | nil,
  created_at: DateTime.t() | nil,
  currency: String.t() | nil,
  current_period_end: DateTime.t() | nil,
  current_period_start: DateTime.t() | nil,
  custom_field_data:
    %{
      required(String.t()) =>
        String.t() | integer() | boolean() | DateTime.t() | nil
    }
    | nil,
  customer: PolarExpress.Schemas.SubscriptionCustomer.t() | nil,
  customer_cancellation_comment: String.t() | nil,
  customer_cancellation_reason:
    PolarExpress.Schemas.CustomerCancellationReason.t() | nil,
  customer_id: String.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,
  ended_at: DateTime.t() | nil,
  ends_at: DateTime.t() | nil,
  id: String.t() | nil,
  metadata: PolarExpress.Schemas.MetadataOutputType.t() | nil,
  meters: [PolarExpress.Schemas.SubscriptionMeter.t()] | nil,
  modified_at: DateTime.t() | nil,
  prices:
    [
      PolarExpress.Schemas.LegacyRecurringProductPrice.t()
      | PolarExpress.Schemas.ProductPrice.t()
    ]
    | nil,
  product: PolarExpress.Schemas.Product.t() | nil,
  product_id: String.t() | nil,
  recurring_interval:
    PolarExpress.Schemas.SubscriptionRecurringInterval.t() | nil,
  recurring_interval_count: integer() | nil,
  seats: integer() | nil,
  started_at: DateTime.t() | nil,
  status: PolarExpress.Schemas.SubscriptionStatus.t() | nil,
  trial_end: DateTime.t() | nil,
  trial_start: DateTime.t() | nil
}