Automapper repro issue 1802

.cs

using System;
using AutoMapper;

namespace ConsoleApplication
{
    public class Source
    {
        public Model Url { get; set; } = new Model();
    }

    public class Model
    {
        public string Content { get; set; }
        public object Other { get; set; }
    }

    public class Dest
    {
        public string Url { get; set; } = "Default";
    }

    public class ModelTypeConverter : ITypeConverter<Model, string>
    {
        public string Convert(Model source, string destination, ResolutionContext context)
        {
            return destination ?? "Broken";
        }
    }

    public class Program
    {
        public static void Main(string[] args)
        {
            var mapper = new MapperConfiguration(conf =>
            {
                conf.CreateMap<Source, Dest>();
                conf.CreateMap<Model, string>().ConvertUsing<ModelTypeConverter>();
            }).CreateMapper();

            var dest = mapper.Map<Source, Dest>(new Source());

            if (dest.Url == "Broken")
            {
                throw new Exception("Default got lost");
            }
        }
    }
}