code: protected void handleFeedImages(List<Pair<String, CharSequence>> params,
                                    Collection<IFeedImage> images) {
      if (images != null && images.size() > 4) {
        throw new IllegalArgumentException("At most four images are allowed, got " +
                                           Integer.toString(images.size()));
      }
      if (null != images && !images.isEmpty()) {
        int image_count = 0;
        for (IFeedImage image : images) {
          ++image_count;
          String imageUrl = image.getImageUrlString(); 
          assert null != imageUrl && "".equals(imageUrl) : "Image URL must be provided";
          params.add(new Pair<String, CharSequence>(String.format("image_%d", image_count),
                                                    image.getImageUrlString()));
          assert null != image.getLinkUrl() : "Image link URL must be provided";
          params.add(new Pair<String, CharSequence>(String.format("image_%d_link", image_count),
                                                    image.getLinkUrl().toString()));
        }
      }
    }
docs: Adds image parameters to a list of parameters
  @param params
  @param images