Adding an example to use raw JSON class instead of target classes (op…

…ensearch-project#385)

Signed-off-by: Vacha Shah <[email protected]>

USER_GUIDE.md

@@ -9,6 +9,7 @@
   - [Create an index](#create-an-index)
   - [Index data](#index-data)
   - [Search for the documents](#search-for-the-documents)
+    - [Get raw JSON results](#get-raw-json-results)
   - [Search documents using a match query](#search-documents-using-a-match-query)
   - [Bulk requests](#bulk-requests)
   - [Aggregations](#aggregations)
@@ -130,6 +131,17 @@ for (int i = 0; i < searchResponse.hits().hits().size(); i++) {
 }
 ```
 
+### Get raw JSON results
+
+When the target class is not defined or if the response result is a semi-structured data not tied to an object definition, use a raw JSON data representation as the target class. For example, the below snippet uses `ObjectNode` from jackson.
+
+```java
+SearchResponse<ObjectNode> searchResponse = client.search(b -> b.index(index), ObjectNode.class);
+for (int i = 0; i < searchResponse.hits().hits().size(); i++) {
+  System.out.println(searchResponse.hits().hits().get(i).source());
+}
+```
+
 ## Search documents using a match query
 
 ```java