code: public static void restoreAntiAliasing (Graphics2D gfx, Object rock)
      {
          if (rock != null) {
              gfx.setRenderingHints((RenderingHints)rock);
          }
      }
docs: Restores anti-aliasing in the supplied graphics context to its original setting.
  
  @param rock the results of a previous call to {@link #activateAntiAliasing} or null, in
  which case this method will NOOP. This alleviates every caller having to conditionally avoid
  calling restore if they chose not to activate earlier.