Support multi-value XPath results about clippit HOT 8 CLOSED

private static string EvaluateXPathToString(XElement element, string xPath, bool optional )
{
    object xPathSelectResult;
    try
    {
        //support some cells in the table may not have an xpath expression.
        if (string.IsNullOrWhiteSpace(xPath)) return string.Empty;

        string[] xPathSplit = xPath.Split('/');

        if (element.Descendants(xPathSplit.Last()).Count() > 1)
        {
            var result = element.Descendants(xPathSplit[xPathSplit.Length - 2]).Select(hl => new
            {
                Str = String.Join(", ", hl.Elements(xPathSplit.Last()).Select(x => x.Value))
            });

            var e = new XElement(xPathSplit.Last(), result.First().Str);

            element.Descendants(xPathSplit.Last()).Remove();

            element.Element(xPathSplit[xPathSplit.Length - 2]).Add(e);

        }

        xPathSelectResult = element.XPathEvaluate(xPath);

    }
    catch (XPathException e)
    {
        throw new XPathException("XPathException: " + e.Message, e);
    }

    if (xPathSelectResult is IEnumerable enumerable and not string)
    {
        var selectedData = enumerable.Cast<XObject>();
        if (!selectedData.Any())
        {
            if (optional) return string.Empty;
            throw new XPathException($"XPath expression ({xPath}) returned no results");
        }

        switch (selectedData.First())
        {
            case XElement xElement:
                return xElement.Value;
            case XAttribute attribute:
                return attribute.Value;
        }
    }

    return xPathSelectResult.ToString();
}