Added json.md - Serialization part

Signed-off-by: Jai2305 <[email protected]>

CHANGELOG.md

@@ -16,6 +16,7 @@ This section is for maintaining a changelog for all breaking changes for the cli
 - Document HTTP/2 support ([#330](https://github.com/opensearch-project/opensearch-java/pull/330))
 - Add support for phase_took & search_pipeline request params ([#1036](https://github.com/opensearch-project/opensearch-java/pull/1036))
 - Add an interface PlainJsonSerializable inherit from JsonpSerializable with a default method streamlining serialization ([#1064](https://github.com/opensearch-project/opensearch-java/pull/1064))
+- Add a new file json.md in guides and SerializationBasics in samples/json ([#1083](https://github.com/opensearch-project/opensearch-java/pull/1083))
 
 ### Dependencies
 

guides/json.md

@@ -0,0 +1,59 @@
+- [Working with Json](#working-with-json)
+  - [Serialization](#serialization)
+    - [Using toJsonString method](#using-tojsonstring-method)
+    - [Manual serialization](#manually-serialize-by-providing-mapper-and-generator)
+
+
+# Working with Json
+
+OpenSearch Java client seamlessly integrate with JSON providing serialization and deserialization capability.
+
+## Serialization
+
+For demonstration let's consider an instance of `SearchRequest`.
+
+```java
+public static void main(final String[] args) {
+  SearchRequest searchRequest = SearchRequest.of(
+          request -> request.index("index1", "index2")
+                  .aggregations(Collections.emptyMap())
+                  .terminateAfter(5L)
+                  .query(q -> q.match(t -> t.field("name").query(FieldValue.of("OpenSearch"))))
+  );
+}
+
+```
+### Using toJsonString method
+For classes implementing `PlainJsonSerializable`, which extends `JsonpSerializable`, a default `toJsonString` method is provided.
+This implementation uses `jakarta.json.spi.JsonProvider` SPI to discover the available JSON provider instance 
+from the classpath and to create a new mapper. The `JsonpUtils` utility class streamlines this serialization process.
+The following code example demonstrates how to use the `toJsonString` method to serialize objects:
+
+```java
+String requestString = searchRequest.toJsonString();
+```
+
+
+### Manually serialize by providing mapper and generator
+For classes implementing the `JsonpSerializable` interface, a serialize method is provided, which takes a mapper and a generator 
+as arguments and returns the JSON string representation of the instance.
+
+The following sample code demonstrates how to serialize an instance of a Java class:
+
+```java
+private String toJson(JsonpSerializable object) {
+  try (StringWriter writer = new StringWriter()) {
+    JsonbJsonpMapper mapper = new JsonbJsonpMapper();
+    try (JsonGenerator generator = mapper.jsonProvider().createGenerator(writer)) {
+      serialize(generator, mapper);
+    }
+    return writer.toString();
+  } catch (IOException ex) {
+    throw new UncheckedIOException(ex);
+  }
+}
+
+```
+
+
+

samples/src/main/java/org/opensearch/client/samples/json/SerializationBasics.java

@@ -0,0 +1,48 @@
+package org.opensearch.client.samples.json;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.opensearch.client.opensearch.OpenSearchClient;
+import org.opensearch.client.opensearch.indices.PutIndexTemplateRequest;
+import org.opensearch.client.opensearch.indices.PutIndexTemplateResponse;
+import org.opensearch.client.samples.SampleClient;
+import org.opensearch.client.samples.Search;
+import java.util.List;
+
+
+public class SerializationBasics {
+
+    private static final Logger LOGGER = LogManager.getLogger(Search.class);
+
+    private static OpenSearchClient client;
+
+    public static void main(String[] args) {
+        try {
+            client = SampleClient.create();
+
+            var version = client.info().version();
+            LOGGER.info("Server: {}@{}.", version.distribution(), version.number());
+
+            final var indexTemplateName = "my-index";
+            final var indexSettingsComponentTemplate = "index-settings";
+            final var indexMappingsComponentTemplate = "index-mappings";
+
+            // Create Index Template Request for index 'my-index'.
+            PutIndexTemplateRequest putIndexTemplateRequest = PutIndexTemplateRequest.of(
+                    it -> it.name(indexTemplateName)
+                            .indexPatterns("my-index-*")
+                            .composedOf(List.of(indexSettingsComponentTemplate, indexMappingsComponentTemplate))
+            );
+
+            LOGGER.info("Creating index template {}.", indexTemplateName);
+
+            // Use toJsonString method to log Request and Response string.
+            LOGGER.debug("Index Template Request: {}.", putIndexTemplateRequest.toJsonString());
+            PutIndexTemplateResponse response = client.indices().putIndexTemplate(putIndexTemplateRequest);
+            LOGGER.info("Index Template Response: {}.", response.toJsonString());
+
+        } catch (Exception e) {
+            LOGGER.error("Exception occurred.", e);
+        }
+    }
+}