code: public void removeDbObject(HsqlName name) {
  
          for (int i = 0; i < map.size(); i++) {
              Grantee g = (Grantee) map.get(i);
  
              g.revokeDbObject(name);
          }
      }
docs: Removes all rights mappings for the database object identified by
  the dbobject argument from all Grantee objects in the set.