@type t() :: %Paypal.Subscription.Plan.Create{
  billing_cycles: [Paypal.Subscription.Plan.BillingCycle.t()],
  description: String.t() | nil,
  name: String.t() | nil,
  payment_preferences: Paypal.Subscription.Plan.PaymentPreferences.t() | nil,
  product_id: String.t() | nil,
  quantity_supported: boolean() | nil,
  status: any() | nil,
  taxes: Paypal.Subscription.Plan.Taxes.t() | nil
}

Fields for creating a billing plan:

• product_id - The product ID (required).
• name - The plan name (required).
• description - Plan description.
• status - Status (:active or :inactive, default :active).
• billing_cycles - List of billing cycle maps/structs (required).
• payment_preferences - Payment preferences map/struct (required).
• taxes - Taxes map/struct.
• quantity_supported - Whether quantity is supported.