docs: @Override
      public String getRootFolderId() {
          if (rootNodeId == null) {
              Document layout = getUserLayoutDOM();
  
              Element rootNode =
                      this.xpathOperations.evaluate("//layout/folder", layout, XPathConstants.NODE);
              if (rootNode == null
                      || !rootNode.getAttribute(Constants.ATT_TYPE)
                              .equals(Constants.ROOT_FOLDER_ID)) {
                  LOG.error(
                          "Unable to locate root node in layout of "
                                  + owner.getUserName()
                                  + ". Resetting corrupted layout.");
                  resetLayout((String) null);
  
                  rootNode =
                          this.xpathOperations.evaluate(
                                  "//layout/folder", layout, XPathConstants.NODE);
                  if (rootNode == null
                          || !rootNode.getAttribute(Constants.ATT_TYPE)
                                  .equals(Constants.ROOT_FOLDER_ID)) {
                      throw new PortalException(
                              "Corrupted layout detected for "
                                      + owner.getUserName()
                                      + " and resetting layout failed.");
                  }
              }
              rootNodeId = rootNode.getAttribute("ID");
          }
          return rootNodeId;
      }