using System;

using System.Threading.Tasks;

public class Program

{

    public static void Main()

    {

        var test = new Test("arg1", async () => 

                            { 

                                return await Task.FromResult("arg2"); 

                            });

    }

}

​

​

public class Test

{

    private readonly string _arg1;

    private readonly Func<Task<string>> _arg2;

    public Test(string arg1, Func<Task<string>> arg2)

    {

        _arg1 = arg1;

        _arg2 = arg2;

    }

}