code: public void setHref(String url) {
          if (url == null)
              throw new RuntimeException("Cannot set URL to null. Call removeUrl() if you wanted to remove the URL");
          if (anchor == null) {
              if (controlGroupRoot != null) {
                  //!!! following code is semi-working, it's not reconstructed item correctly
                  remove(controlGroupRoot);
                  anchor = Document.get().createAnchorElement();
                  anchor.setAttribute("href", url);
                  moveThisChildrenToAnchor();
                  cleanUpLI();
                  prepareAnchorForControlGroup();
                  getElement().appendChild(anchor);
                  checkAnchorPanel();
              } else {
                  // need to make anchor and move children to it
                  anchor = Document.get().createAnchorElement();
                  moveThisChildrenToAnchor();
                  getElement().appendChild(anchor);
              }
              addItemActivationHandlers();
          }
          anchor.setAttribute("href", url);
      }
docs: Sets the url to link to for this item. If this item was a read only
  item it automatically becomes linkable.