@type t() :: %Polarex.EventCreateExternalCustomer{
  external_customer_id: String.t(),
  external_id: String.t() | nil,
  metadata: Polarex.EventMetadataInput.t() | nil,
  name: String.t(),
  organization_id: String.t() | nil,
  parent_id: String.t() | nil,
  timestamp: DateTime.t() | nil
}