code: private boolean checkParents(boolean exclusive) {
          if (_path.equals("/")) {
              return true;
          } else {
              if (_owner == null) {
                  // no owner, checking parents
                  return _parent != null && _parent.checkParents(exclusive);
              } else {
                  // there already is a owner
                  return !(_exclusive || exclusive)
                          && _parent.checkParents(exclusive);
              }
          }
      }
docs: helper of checkLocks(). looks if the parents are locked
  
  @param exclusive
  wheather the new lock should be exclusive
  @return true if no locks at the parent path are forbidding a new lock