code: protected boolean checkLocks ()
      {
          if (_rebootLocks.isEmpty()) {
              return false;
          }
  
          log.info("Reboot delayed due to outstanding locks", "locks", _rebootLocks.elements());
          broadcast("m.reboot_delayed");
          (_interval = _omgr.newInterval(new Runnable() {
              public void run () {
                  doWarning(getWarnings().length, 0);
              }
          })).schedule(60 * 1000);
          return true;
      }
docs: Check to see if there are outstanding reboot locks that may delay the reboot, returning
  false if there are none.