Web API 2 response design issue

I'm having some design problems (I think) and are looking for advice/alternative solutions. I have some base classes and one interface.

public interface IBuildLinks
{
    void BuildLinks(Uri root);
}

public abstract class AbstractModel : IBuildLinks
{
    public void BuildLinks(Uri root)
    {
    }
}

public abstract class AbstractCollectionModel<T> where T : AbstractModel, IBuildLinks
{
    public List<T> Items { get; set; }

    public void BuildLinks(Uri root)
    {
    }
}

And some implementations of these classes:

public class AssortmentModel : AbstractModel
{
}

public class AssortmentCollectionModel : AbstractCollectionModel<AssortmentModel>
{
}

I have a filter that should call BuildLinks if the response is a type that implements IBuildLinks

public class BuildModelLinksFilterAttribute : ActionFilterAttribute
{
    public override void OnActionExecuted(HttpActionExecutedContext context)
    {
        var content = context.Response.Content as ObjectContent;
        if (content == null)
        {
            return;
        }

        var type = content.ObjectType;

        if (type.IsAssignableFrom(typeof(IBuildLinks)))
        {
            var value = (IBuildLinks)content.Value;
            var root = context.Request.GetRootUrl();

            value.BuildLinks(new Uri(root));
        }
    }
}

Unfortunately this does not work since derived types like AssortmentCollectionModel is not recognized as implementing IBuildLinks

If I slap the IBuildLinks interface on every derived class it does work. It feels like there is a better way to do this so I'm looking for suggestions on how to improve the code. Perhaps I could do this fundamentally different in some way?