public Map<String, Object> toSource() {
        Map<String, Object> sourceMap = new HashMap<>();
        if (urlId != null) {
            addFieldToSource(sourceMap, "urlId", urlId);
        }
        if (docId != null) {
            addFieldToSource(sourceMap, "docId", docId);
        }
        if (order != null) {
            addFieldToSource(sourceMap, "order", order);
        }
        if (queryId != null) {