public class Class1
    {
        private readonly MyCollection _items = [];
        public int CurrentCount => _items.Count;
        public void AddItem(int value)
        {
            _items.Add(value);
        }
    }
    internal sealed class MyCollection
        : Collection<int>
    {

    }
    public class Class2
    {
#pragma warning disable IDE0028 // Simplify collection initialization
        private readonly MyCollection2 _items = new();
#pragma warning restore IDE0028 // Simplify collection initialization
    }
    internal sealed class MyCollection2
        : Collection<int>
    {

    }

  Error CA1812: 'MyCollection' is an internal class that is apparently never instantiated. If so, remove the code from the assembly. If this class is intended to contain only static members, make it 'static' (Module in Visual Basic). (https://learn.microsoft.com/dotnet/fundamentals/code-analysis/quality-rules/ca1812) (14, 27)