I am using C# records in a HashSet to enforce uniqueness. This works well, but as soon as the record contains a Collection then it stops working.

ie. this passes:

public record Person
{
    public string FirstName { get; set; }
}

HashSet<Person> uniquePeople = new();
uniquePeople.Add(new Person { FirstName = "John" });
uniquePeople.Add(new Person { FirstName = "John" });
Assert.That(uniquePeople.Count() == 1);

But this fails:

public record Person
{
    public string FirstName { get; set; }
    public HashSet<int> FavouriteNumbers { get; set; } = new();
}

HashSet<Person> uniquePeople = new();
uniquePeople.Add(new Person { FirstName = "John" });
uniquePeople.Add(new Person { FirstName = "John" });
Assert.That(uniquePeople.Count() == 1);

How can I enforce uniqueness on nested collections using records?