private void OnValidationCountChanged()
        {
            //if (TopNode != null)
            //{
            //    SetXmlNodeString("@count", _validations.Count.ToString());
            //}
            var dvNode = GetRootNode();

            if (_validations.Count == 0)
            {
                if (dvNode != null)
                {
                    _worksheet.WorksheetXml.DocumentElement.RemoveChild(dvNode);
                }
                _worksheet.ClearValidations();
            }
            else
            {
                var attr = _worksheet.WorksheetXml.DocumentElement.SelectSingleNode(DataValidationPath + "[@count]", _worksheet.NameSpaceManager);
                if (attr == null)
                {
                    dvNode.Attributes.Append(_worksheet.WorksheetXml.CreateAttribute("count"));
                }
                dvNode.Attributes["count"].Value = _validations.Count.ToString(CultureInfo.InvariantCulture);
            }
        }