*
   * @since 14.0
   */
  @J2ktIncompatible
  @GwtIncompatible // concurrency
  public static ThreadFactory platformThreadFactory() {
    if (!isAppEngineWithApiClasses()) {
      return defaultThreadFactory();
    }
    try {
      return (ThreadFactory)
          Class.forName("com.google.appengine.api.ThreadManager")