code: public static Integer asInteger(String expression, Node node, XPath xpath)
              throws XPathExpressionException {
          String intString = evaluateAsString(expression, node, xpath);
          return (isEmptyString(intString)) ? null : Integer.parseInt(intString);
      }
docs: Same as {@link #asInteger(String, Node)} but allows an xpath to be passed
  in explicitly for reuse.