getAllKeys method
Implementation
Future<List<String>> getAllKeys([Transaction? txn]) async {
if (_keysCached) return _cachedKeys!.toList();
txn ??= boxCollection._db.transaction(name, 'readonly');
final store = txn.objectStore(name);
print('Load all keys');
final request = store.getAllKeys(null);
await request.onSuccess.first;
final keys = request.result.cast<String>();
_cachedKeys = keys.toSet();
return keys;
}