static <T> List<T> nullToEmptyList(@Nullable List<T> items) {
    return items != null ? items : Collections.emptyList();
  }
@param service the name of the service
@param quickLink the quicklink
@return a boolean indicating whether the link in the parameter should be visible
ambari-server/src/main/java/org/apache/ambari/server/state/quicklinksprofile/DefaultQuickLinkVisibilityController.java