Issue where properties in derived types are not assigned

[sommmen]

Hiya, i think i'm doing something stupid or this is a bug.

Consider the following code:

using System;
using System.Collections.Generic;
using AutoMapper;

public class OrderViewModel {
	public Guid Id {get;set;}
}

public class OrderSummaryViewModel : OrderViewModel {
	public int NumberOfLines {get;set;}
}

public class MyGenericResponseObject<T> {
	public List<T> Items {get;set;} = new();
}

public class MyResponseObject : MyGenericResponseObject<OrderSummaryViewModel> {
}

public class Program
{
	public static void Main()
	{
		var e1 = new MyGenericResponseObject<OrderSummaryViewModel>
		{
			Items = new() {
				new() { Id = Guid.NewGuid(), NumberOfLines = 420 }
			}
		};

		var config = new MapperConfiguration(cfg =>
		{
			cfg.CreateMap<OrderSummaryViewModel, OrderViewModel>();
			cfg.CreateMap<OrderViewModel, OrderSummaryViewModel>();
			cfg.CreateMap<MyGenericResponseObject<OrderSummaryViewModel>, MyResponseObject>();
		});

		var mapper = config.CreateMapper();

		var e2 = mapper.Map<MyGenericResponseObject<OrderSummaryViewModel>, MyResponseObject>(e1);

		foreach (var i in e1.Items)
		{
			Console.WriteLine($"{i.Id} - {i.NumberOfLines}");
		}

		Console.WriteLine("------------------");

		foreach (var i in e2.Items)
		{
			Console.WriteLine($"{i.Id} - {i.NumberOfLines}");
		}
	}
}

https://dotnetfiddle.net/tcoRvK

Now since the type of e1 is MyGenericResponseObject<OrderSummaryViewModel> i'm expecting the two lists to be equal after the mapping. Instead it outputs the following:

701cde6c-4751-4419-a2cb-1d347a3eb0e6 - 420
------------------
701cde6c-4751-4419-a2cb-1d347a3eb0e6 - 0

For some reason after the mapping the NumberOfLines property is its default...
How come? is there something wrong with my configuration perhaps - or is it a limitation of AutoMapper or is it a bug?
Any help would be welcome.

using net6 and latest stable automapper (see the fiddle).

[lbargaoanu]

I think this is better suited for StackOverflow.

[sommmen]

Cross posted on SO;
https://stackoverflow.com/questions/74860166/automapper-issue-where-properties-in-in-derived-types-are-not-assigned