code: protected final String buildDummyImageUrl(MediaFormat format) {
      String suffix = new SuffixBuilder()
      .put(DummyImageServlet.SUFFIX_WIDTH, format.getWidth())
      .put(DummyImageServlet.SUFFIX_HEIGHT, format.getHeight())
      .put(DummyImageServlet.SUFFIX_MEDIA_FORMAT_NAME, format.getLabel())
      .build();
      return urlHandler.get(DummyImageServlet.PATH)
          .extension(FileExtension.PNG)
          .suffix(suffix)
          .build();
    }
docs: Build Dummy/Placeholder image URL
  @param format Media format
  @return Dummy image URL