}
  }

  @Override
  public final boolean isRunning() {
    return state() == RUNNING;
  }

  @Override
  public final State state() {
    return snapshot.externalState();
  }

  /** @since 14.0 */
  @Override
  public final Throwable failureCause() {
    return snapshot.failureCause();
  }

  /** @since 13.0 */
  @Override