code: protected String readACLOwner(String cid) throws SQLException, IllegalACLException
     {
        ResultSet exoOwner = findPropertyByName(cid, Constants.EXO_OWNER.getAsString());
        try
        {
           if (exoOwner.next())
           {
              return new String(exoOwner.getBytes(COLUMN_VDATA));
           }
           else
           {
              throw new IllegalACLException("Property exo:owner is not found for node with id: " + getIdentifier(cid));
           }
        }
        finally
        {
           try
           {
              exoOwner.close();
           }
           catch (SQLException e)
           {
              LOG.error("Can't close the ResultSet: " + e.getMessage());
           }
        }
     }
docs: Return owner value or throw an exception. We assume the node is mix:owneable.
  
  @param cid
  Node id
  @return ACL owner
  @throws SQLException
  database error
  @throws IllegalACLException
  Property exo:owner is not found for node