public ImageUrlsRequestBuilder addImageFormat(ImageFormat imageFormat, ImageSize imageSize) {
    mRequestedImageFormats.put(imageFormat, imageSize);
    return this;
  }
Adds imageFormat to the set of image formats you want to download. imageSize specify
server-side resize options.
samples/comparison/src/main/java/com/facebook/samples/comparison/urlsfetcher/ImageUrlsRequestBuilder.java