@type t() ::
  %Stripe.Params.TestHelpers.Issuing.TransactionCreateUnlinkedRefundParams.PurchaseDetails.Flight{
    departure_at: integer() | nil,
    passenger_name: String.t() | nil,
    refundable: boolean() | nil,
    segments:
      [
        Stripe.Params.TestHelpers.Issuing.TransactionCreateUnlinkedRefundParams.PurchaseDetails.Flight.Segments.t()
      ]
      | nil,
    travel_agency: String.t() | nil
  }