addEventSources method
Implementation
@override
Future<void> addEventSources({
required String eventId,
required Iterable<String> relayUrls,
}) async {
await dbRdy;
final sources = _eventSources.putIfAbsent(eventId, () => <String>{});
sources.addAll(relayUrls);
final sortedSources = sources.toList()..sort();
_upsertKeyValue(_eventSourcesKey(eventId), jsonEncode(sortedSources));
}