docs: public static List<Element> getChildElements(final Element elem, final String ns, final String name) {
          final NodeList children =  elem.getChildNodes();
          final List<Element> res = new ArrayList<>(children.getLength());
          for (int i = 0; i < children.getLength(); i++) {
              final Node child = children.item(i);
              if (child.getNodeType() == Node.ELEMENT_NODE) {
                  if (Objects.equals(child.getNamespaceURI(), ns) && name.equals(child.getLocalName())) {
                      res.add((Element) child);
                  }
              }
          }
          return res;
      }