docs: @Override
      public IPortletUrlBuilder getPortletUrlBuilder(IPortletWindowId portletWindowId) {
          IPortletUrlBuilder portletUrlBuilder;
  
          portletUrlBuilder = this.portletUrlBuilders.get(portletWindowId);
          if (portletUrlBuilder == null) {
              portletUrlBuilder =
                      ConcurrentMapUtils.putIfAbsent(
                              this.portletUrlBuilders,
                              portletWindowId,
                              new PortletUrlBuilder(portletWindowId, this));
          }
  
          return portletUrlBuilder;
      }