public object DeepClone()
        {
            var clone = new PropertyGroupCollection();

            foreach (var group in this)
            {
                clone.Add((PropertyGroup)group.DeepClone());
            }
            return(clone);
        }
        public object DeepClone()
        {
            var newGroup = new PropertyGroupCollection();

            foreach (var p in this)
            {
                newGroup.Add((PropertyGroup)p.DeepClone());
            }
            return(newGroup);
        }