@type t() :: %Paypal.Subscription.ReviseResponse{
  links: [Paypal.Common.Link.t()],
  plan_id: String.t() | nil,
  plan_overridden: boolean() | nil,
  quantity: String.t() | nil
}

Subscription revise response:

• plan_id - Updated plan ID.
• quantity - Updated quantity.
• plan_overridden - Whether the plan was overridden.
• links - HATEOAS links (e.g. approve link).