code: @SuppressWarnings("null")
    protected JSONObject toReponsiveImageSource(Media media, Rendition rendition) {
      try {
        JSONObject source = new JSONObject();
        MediaFormat mediaFormat = rendition.getMediaFormat();
        source.put(MediaNameConstants.PROP_BREAKPOINT, mediaFormat.getProperties().get(MediaNameConstants.PROP_BREAKPOINT));
        source.put(PROP_SRC, rendition.getUrl());
        return source;
      }
      catch (JSONException ex) {
        throw new RuntimeException("Error building JSON source.", ex);
      }
    }
docs: Build JSON metadata for one rendition as image source.
  @param media Media
  @param rendition Rendition
  @return JSON metadata