using System;

using System.Threading.Tasks;

using System.Linq;

​

#nullable enable

public class Program

{

    public static async void Main()

    {

        Task? task1 = null;

        Task? task2 = null;

        Task? task3 = null;

        await Task.WhenAll(new Task?[] { task1,task2,task3 }.Where(t => t is not null));

    }

}