using System;

​

public class Program

{

  public static void Main(string[] args)

  {

    var before = new ArgumentException(null, nameof(args)).Message;

    var after = new ArgumentException(new ArgumentException().Message, nameof(args)).Message;

​

    Console.WriteLine($"Before:\r\n{before}\r\n\r\nAfter:\r\n{after}\r\n");

    Console.WriteLine($"Passing null matches no parameter: {before == after}");

  }

}

​