private Map<String, String> getUserInputs(Query q) {
        Map<String, String> param = new HashMap<>();
        q.queries.forEach(qu -> {
            if (qu instanceof Query) {
                param.putAll(getUserInputs((Query) qu));
            }
        });
        return param;
    }
Builds the vespa query string joined by '&amp;'

@return the query string
client/src/main/java/ai/vespa/client/dsl/FixedQuery.java