code: public RequestConfig withOptions(Heroku.RequestKey key, Map<String, String> data) {
          RequestConfig newConfig = copy();
          newConfig.config.put(key, new Either(new Data(data)));
          return newConfig;
      }
docs: Sets a {@link com.heroku.api.Heroku.RequestKey} parameter.
  @param key Heroku request key
  @param data arbitrary key/value map
  @return A new {@link RequestConfig}