public static String serialize(Query query) {
        return serialize(query, "");
    }
Do YQL+ escaping, which is basically the same as for JSON, of the
incoming string to the "quoted" buffer. The buffer returned is the same
as the one given in the "quoted" parameter.

@param in a string to escape
@param escaped the target buffer for escaped data
@return the same buffer as given in the "quoted" parameter
container-search/src/main/java/com/yahoo/search/yql/VespaSerializer.java