getDeadLetter method
Fetches a single dead-letter entry by id.
Implementation
@override
/// Fetches a single dead-letter entry by id.
Future<DeadLetterEntry?> getDeadLetter(String queue, String id) async {
final state = _state(queue);
return state.deadLetters.firstWhereOrNull(
(entry) => entry.envelope.id == id,
);
}