docs: private boolean isValidationMatcherExpression(Node node) {
          switch (node.getNodeType()) {
              case Node.ELEMENT_NODE:
                  return node.getFirstChild() != null &&
                  StringUtils.hasText(node.getFirstChild().getNodeValue()) &&
                  ValidationMatcherUtils.isValidationMatcherExpression(node.getFirstChild().getNodeValue().trim());
  
              case Node.ATTRIBUTE_NODE:
                  return StringUtils.hasText(node.getNodeValue()) &&
                  ValidationMatcherUtils.isValidationMatcherExpression(node.getNodeValue().trim());
  
              default: return false; //validation matchers makes no sense
          }
      }