code: private String xPathEvaluate(Object input) {
          JAXPXPathEngine engine = xpf == null ? new JAXPXPathEngine() : new JAXPXPathEngine(xpf);
          if (prefix2Uri != null) {
              engine.setNamespaceContext(prefix2Uri);
          }
  
          Source s = Input.from(input).build();
          Node n = dbf != null ? Convert.toNode(s, dbf) : Convert.toNode(s);
          return engine.evaluate(xPath, n);
      }
docs: Evaluates the provided XML input to the configured <code>xPath</code> field XPath expression.
  @param input an XML input
  @return the result of the XPath evaluation