code: protected Node getXPathResultNode(String select, Document document)
          throws ConfigurationException, TransformerException, XpathException {
          return getXPathResultAsDocument(select, document).getDocumentElement();
      }
docs: Testable method to execute the copy-of transform and return the root
  node of the resulting Document.
  @param select
  @param document
  @throws ConfigurationException
  @throws TransformerException
  @return the root node of the Document created by the copy-of transform.