@type t() :: %Polarex.CustomerUpdate{
  billing_address: Polarex.AddressInput.t() | nil,
  email: String.t() | nil,
  external_id: String.t() | nil,
  locale: String.t() | nil,
  metadata: map() | nil,
  name: String.t() | nil,
  tax_id: String.t() | nil,
  type: String.t() | nil
}