NavObjectNode.cs

public class NavObjectNode
{
    private readonly int _type;
    private readonly int _id;
    private readonly List<NavObjectNode> _compositionList;

    public NavObjectNode(int type, int id)
    {
        _type = type;
        _id = id;
        _compositionList = new List<NavObjectNode>();
    }

    public IList<NavObjectNode> ComposedOf
    {
        get { return _compositionList; }
    }

    public int Type
    {
        get { return _type; }
    }

    public int Id
    {
        get { return _id; }
    }

    public void AddCompositionNavObject(NavObjectNode navObject)
    {
        // avoid self reference... it happens in tables sometimes
        if (navObject.Id == Id && navObject.Type == Type) return;

        if (!_compositionList.Contains(navObject))
        {
            _compositionList.Add(navObject);
        }
    } 
    // remaining details omitted
}