docs: private Visualization embedOrThumbnail(final int thumbsize, PlotItem it, VisualizationTask task, Element parent) {
      final Visualization vis;
      if(!single) {
        vis = task.getFactory().makeVisualizationOrThumbnail(context, task, plot, it.w, it.h, it.proj, thumbsize);
      }
      else {
        vis = task.getFactory().makeVisualization(context, task, plot, it.w, it.h, it.proj);
      }
      if(vis == null || vis.getLayer() == null) {
        LOG.warning("Visualization returned empty layer: " + vis);
        return vis;
      }
      if(task.has(RenderFlag.NO_EXPORT)) {
        vis.getLayer().setAttribute(SVGPlot.NO_EXPORT_ATTRIBUTE, SVGPlot.NO_EXPORT_ATTRIBUTE);
      }
      parent.appendChild(vis.getLayer());
      return vis;
    }