// Convenience public static Task WhenInvokeAll <TEventArgs>( this AsyncEventHandler <TEventArgs> handler, object sender, TEventArgs e) where TEventArgs : EventArgs => Task.WhenAll(handler.InvokeAll(sender, e));
// Convenience public static Task WhenInvokeAll <TEventArgs>( this AsyncEventHandler <TEventArgs> handler, object sender, TEventArgs e) where TEventArgs : EventArgs => Task.WhenAll(handler.InvokeAll(sender, e));