@Override
 public FilterConditionContext or(FilterConditionContext rightCondition) {
   // todo [anistor] check rightCondition does not already belong to a builder
   combine(false, rightCondition);
   return this;
 }
 @Override
 public FilterConditionBeginContext or() {
   IncompleteCondition rightCondition = new IncompleteCondition();
   combine(false, rightCondition);
   return rightCondition;
 }