public async Task AddManualStackSignatureData(string stackingKey, bool willAddManualStackSignature) {
var ev = new PersistentEvent();
ev.SetManualStackingKey(stackingKey);
var context = new EventContext(ev);
var plugin = new ManualStackingPlugin();
await plugin.EventBatchProcessingAsync(new List<EventContext> { context });
Assert.Equal(willAddManualStackSignature, context.StackSignatureData.Count > 0);
}