using System;

using System.Linq;

using System.Collections;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var id = Guid.NewGuid();

        var x = new MyClass(new List<MySub> { new(id) });

        var y = new MyClass(new List<MySub> { new(id) });

        var comparer = new ObjectsComparer.Comparer<MyClass>();

        Console.WriteLine(comparer.Compare(x, y));

    }

    public record MyClass(IReadOnlyCollection<MySub> Subs) : IComparable<MyClass>

    {       

        public int CompareTo(MyClass other)

        {           

            if (ReferenceEquals(this, other))

            {

                return 0;

            }

​

            if (ReferenceEquals(null, other))

            {

                return 1;

            }

​

            return Subs.First().Id.CompareTo(other.Subs.First().Id);

        }

    }

    public record MySub(Guid Id);

}