@Override
        boolean serialize(StringBuilder destination, StringInItem item) {
            destination.append(item.getIndexName()).append(" in (");
            int initLen = destination.length();
            List<String> tokens = new ArrayList<>(item.getTokens());
            Collections.sort(tokens);
            for (var token : tokens) {
                comma(destination, initLen);
                destination.append('"');
                escape(token, destination);
                destination.append("\"");
            }
            destination.append(")");
            return false;
        }
Serialize Vespa query trees to YQL+ strings.

@author Steinar Knutsen
container-search/src/main/java/com/yahoo/search/yql/VespaSerializer.java