void setReplacing(boolean replacing) {
        for (Iterator<Production> i = productions.iterator(); i.hasNext(); ) {
            Production production = i.next();
            production.setReplacing(replacing);
        }

        this.replacing = replacing;
    }
True to replace, false to add, default true
container-search/src/main/java/com/yahoo/prelude/semantics/rule/ProductionList.java