code: public boolean start() {
          if (!this.isStarted.compareAndSet(false, true)) {
              return false;
          }
          final long delay = this.delayBetweenSweeps;
          this.timer.scheduleWithFixedDelay(this, delay, delay, TimeUnit.MILLISECONDS);
          LogWatchStorageSweeper.LOGGER.info(
                  "Scheduled automated unreachable message sweep in {} to run every {} millisecond(s).",
                  this.messaging.getLogWatch(), delay);
          return true;
      }
docs: Start the sweeping if not started already.
  
  @return False if already called before, true otherwise.