internal XmlDocument HandleConversion(XmlDocument doc)
        {
            // TODO: do we want to continue if one of the chain operation failed?
            var resultDocument = DoHandleConversion(doc);

            Debug.Assert(resultDocument != null, "The document returned by metadata converter is null");

            if (_successor != null &&
                resultDocument != null)
            {
                resultDocument = _successor.HandleConversion(resultDocument);
            }
            return(resultDocument);
        }