* Executor#execute(Runnable) execute()} method is called when this service is started and
   * stopped, and should return promptly.
   */
  protected Executor executor() {
    return command -> MoreExecutors.newThread(threadNameSupplier.get(), command).start();
  }

  @Override
  public String toString() {
    return serviceName() + " [" + state() + "]";
  }

  @Override
  public final boolean isRunning() {