@type t() :: %MBTA.Model.AlertResourceAttributes{
  active_period: [MBTA.Model.ActivePeriod.t()] | nil,
  banner: String.t() | nil,
  cause: String.t() | nil,
  created_at: DateTime.t() | nil,
  description: String.t() | nil,
  effect: String.t() | nil,
  effect_name: String.t() | nil,
  header: String.t() | nil,
  image: String.t() | nil,
  image_alternative_text: String.t() | nil,
  informed_entity: [MBTA.Model.InformedEntity.t()] | nil,
  lifecycle: String.t() | nil,
  service_effect: String.t() | nil,
  severity: integer() | nil,
  short_header: String.t() | nil,
  timeframe: String.t() | nil,
  updated_at: DateTime.t() | nil,
  url: String.t() | nil
}