models

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

    public string Name { get; set; }
}

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

    public string Name { get; set; }
}

public class RegionV2: Region
{
    public IEnumerable<City> Cities { get; set; }

    public bool HasContragents { get; set; }
}