@type t() :: %Dnsimple.DomainRegistration{
  auto_renew: boolean(),
  created_at: String.t(),
  domain_id: integer(),
  expires_on: term(),
  id: integer(),
  period: integer(),
  registrant_id: integer(),
  state: String.t(),
  updated_at: String.t(),
  whois_privacy: boolean()
}