code: public static ConfigDef.Recommender visibleIf(String configKey, Object value) {
      return new VisibleIfRecommender(configKey, value, ValidValuesCallback.EMPTY);
    }
docs: Method is used to return a recommender that will mark a ConfigItem as visible if
  the configKey is set to the specified value.
  
  @param configKey The setting to retrieve the value from.
  @param value     The expected value.
  @return recommender