for (Map<String, Object> existingDoc : existingDocs) {
            final Map<String, Object> doc = new HashMap<>();
            doc.put("doc_id", existingDoc.get("doc_id"));
            doc.put("title", existingDoc.get("title") + "_updated");
            doc.put("url", existingDoc.get("url_link"));
            doc.put("content", "Updated content");