code: public void addHiDpiImage(String factor, CmsJspImageBean image) {
  
          if (m_hiDpiImages == null) {
              m_hiDpiImages = CmsCollectionsGenericWrapper.createLazyMap(new CmsScaleHiDpiTransformer());
          }
          m_hiDpiImages.put(factor, image);
      }
docs: adds a CmsJspImageBean as hi-DPI variant to this image
  @param factor the variant multiplier, e.g. "2x" (the common retina multiplier)
  @param image the image to be used for this variant