Task2.cs

public class AsyncCaller : IAsyncDisposable
{
    private System.Timers.Timer _timer;
    private readonly CancellationTokenSource _tokenSource;
    private readonly EventHandler Handler;
    private bool _completedOk;
  
    public AsyncCaller(EventHandler h)
    {
        _tokenSource = new CancellationTokenSource();
        Handler = h;
        _timer = null!;
        _tokenSource.Token.Register(() => _completedOk = false);
    }

    private void OnTimedEvent(object? sender, ElapsedEventArgs e)=> _tokenSource.Cancel();

    public bool Invoke(int milliseconds, object? sender, EventArgs eventArgs)
    {
        _completedOk = false;
        _timer = new System.Timers.Timer(milliseconds);
        _timer.Elapsed += OnTimedEvent;
        _timer.Enabled = true;

        return _completedOk;
    }

    public async Task SomeMethod(CancellationToken token)
    {
        var beginInvoke = Handler.BeginInvoke(null, EventArgs.Empty, null, null);
        while (beginInvoke.IsCompleted)
        {

            if (!token.IsCancellationRequested)
                Thread.Sleep(50);
            return;
        }
    }

    public async ValueTask DisposeAsync()
    {
        _timer.Dispose();
        _tokenSource.Dispose();
        GC.SuppressFinalize(this);
    }
}