docs: public long getLastModified() throws GetLastModifiedException {
          long result;
  
          result = Long.MIN_VALUE;
          for (Node node : nodes) {
              if (node instanceof HttpNode) {
                  // skip getLastModified - it's not supported by Webservice Stub Servlet
              } else {
                  result = Math.max(result, node.getLastModified());
              }
          }
          return result == Long.MIN_VALUE ? -1 : result;
      }