@type t() :: %Observer.Web.Apps.Identifier{
  fetched_at: integer() | nil,
  id_string: String.t() | nil,
  info: ObserverWeb.Apps.Process.t() | ObserverWeb.Apps.Port.t() | nil,
  memory_monitor: boolean(),
  metric: String.t() | nil,
  node: atom() | nil,
  type: nil
}