create method
If no mapping exists for key, associates it with value and
returns the commit-log sequence number; otherwise behaviour is
implementation-defined (typically throws).
Returns the commit-log sequence number assigned to this write,
or null if no sequence number was produced.
Throws a DataStoreException if the underlying store fails.
Implementation
@override
Future<int?> create(key, value, {bool skipCommit = false}) async {
// Notification keystore doesn't distinguish create-vs-update;
// delegate to put() which atomically sets the entry regardless.
return put(key, value, skipCommit: skipCommit);
}