code: private void addHighlights(Collection<? extends Point> points, Color color)
      {
          removeHighlights(points);
          Map<Point, Object> newHighlights = 
              JTextComponents.addHighlights(textComponent, points, color);
          highlights.putAll(newHighlights);
      }
docs: Add highlights with the given color to the text component for all
  the given points
  
  @param points The points, containing start and end indices
  @param color The color