docs: private @Nonnull NodeList evaluate(String xpath) {
          try {
              XPathExpression expr = xpf.newXPath().compile(xpath);
              return (NodeList) expr.evaluate(node, XPathConstants.NODESET);
          } catch (XPathExpressionException ex) {
              throw new IllegalArgumentException("Invalid XPath '" + xpath + "'", ex);
          }
      }