protected String toInnerString(String conditionSeparator) {
        if (getLabel() != null)
            return getLabel() + ":(" + conditionsToString(conditionSeparator) + ")";
        else if (useParentheses())
            return "(" + conditionsToString(conditionSeparator) + ")";
        else
            return conditionsToString(conditionSeparator);
    }
Whether this should be output with parentheses, default is parent!=null
container-search/src/main/java/com/yahoo/prelude/semantics/rule/CompositeCondition.java