/** Constructor for use by subclasses. */
  protected AbstractScheduledService() {}

  /**
   * Run one iteration of the scheduled task. If any invocation of this method throws an exception,
   * the service will transition to the {@link Service.State#FAILED} state and this method will no
   * longer be called.
   */
  protected abstract void runOneIteration() throws Exception;

  /**
   * Start the service.
   *