protected void xscalarCondition(String function, SubQuery<RegionCB> subQuery, String operand) {
assertObjectNotNull("subQuery<RegionCB>", subQuery);
RegionCB cb = new RegionCB();
cb.xsetupForScalarCondition(this);
subQuery.query(cb);
String subQueryPropertyName = keepScalarCondition(cb.query()); // for saving query-value.
registerScalarCondition(function, cb.query(), subQueryPropertyName, operand);
}
