*/
  public ThreadFactory build() {
    return doBuild(this);
  }

  // Split out so that the anonymous ThreadFactory can't contain a reference back to the builder.
  // At least, I assume that's why. TODO(cpovirk): Check, and maybe add a test for this.
  @SuppressWarnings("ThreadPriorityCheck") // We only propagate user requests (which we discourage).
  private static ThreadFactory doBuild(ThreadFactoryBuilder builder) {