public String toContentString() {
        StringBuilder b = new StringBuilder();
        for (Iterator<ProductionRule> i = productionRules.iterator(); i.hasNext(); ) {
            b.append(i.next());
            b.append("\n");
        }
        b.append("\n");
        b.append("\n");
        for (Iterator<NamedCondition> i = namedConditions.values().iterator(); i.hasNext(); ) {
            b.append(i.next());
            b.append("\n");
        }
        return b.toString();
    }
Returns a string containing all the rules and conditions of this rule base
in the form they will be evaluated, with all included rule bases inlined
container-search/src/main/java/com/yahoo/prelude/semantics/RuleBase.java