AutoMapper_8_1_0_ListFail.cs

class Program
{
	static void Main(string[] args)
	{
		var config = new MapperConfiguration(c =>
		{
			c.CreateMap<SourceClass, TargetClass>()
				.ForMember(x => x.Vals, o => o.MapFrom((srcCls, trgCls) =>
				{
					trgCls.Vals.Clear();
					trgCls.Vals.AddRange(srcCls.Vals);
					return trgCls.Vals;
				}));
		});

		config.AssertConfigurationIsValid();
		IMapper mapper = new Mapper(config);

		var src = new SourceClass();
		var trg = mapper.Map<TargetClass>(src);

		Console.WriteLine(string.Join('|', trg.Vals));
	}
}


class SourceClass
{
	public SourceClass()
	{
		Vals = new List<int> { 1, 2, 3 };
	}

	public List<int> Vals { get; set; }
}


class TargetClass
{
	private List<int> _vals = new List<int>();

	public List<int> Vals => _vals;
}