* Helper method to update a single column in a database row.
*/
protected void updateRow(ObjectId id, String dbAttribute, Object newValue) {
UpdateQuery updateQuery = new UpdateQuery();
updateQuery.setRoot(id.getEntityName());
updateQuery.addUpdAttribute(dbAttribute, newValue);
// set qualifier
updateQuery.setQualifier(ExpressionFactory.matchAllDbExp(
id.getIdSnapshot(),
Expression.EQUAL_TO));