code: public static ImageOption http() {
      return new ImageOption("http", "") {
        @Override public String apply(String url) {
          if (url.startsWith("//")) {
            return "http:" + url;
          } else {
            return url;
          }
        }
      };
    }
docs: Prefix image urls with http.
  <p>
  If a protocol (either http or https) was already specified, this one will be taken and
  this option will not have any effect.
  
  @return an image option changing a given url to use insecure http transport.