adding chunk support for non-compressed request

Signed-off-by: Jitendra Kumar <jkjitend@amazon.com>

client/rest/src/main/java/org/opensearch/client/RestClient.java

@@ -36,6 +36,7 @@
 import org.apache.http.ConnectionClosedException;
 import org.apache.http.Header;
 import org.apache.http.HttpEntity;
+import org.apache.http.entity.HttpEntityWrapper;
 import org.apache.http.HttpHost;
 import org.apache.http.HttpRequest;
 import org.apache.http.HttpResponse;
@@ -644,6 +645,8 @@ private static HttpRequestBase addRequestBody(
                     } else {
                         entity = new ContentCompressingEntity(entity);
                     }
+                } else if (chunkedTransferEncodingEnabled) {
+                    entity = new ChunkedHttpEntity(entity);
                 }
                 ((HttpEntityEnclosingRequestBase) httpRequest).setEntity(entity);
             } else {
@@ -1045,6 +1048,28 @@ public long getContentLength() {
         }
     }
 
+    public static class ChunkedHttpEntity extends HttpEntityWrapper {
+        /**
+         * Creates a {@link ChunkedHttpEntity} instance with the provided HTTP entity.
+         *
+         * @param entity the HTTP entity.
+         */
+        public ChunkedHttpEntity(HttpEntity entity) {
+            super(entity);
+        }
+
+        /**
+         * A chunked entity requires transfer-encoding:chunked in http headers
+         * which requires isChunked to be true
+         *
+         * @return true
+         */
+        @Override
+        public boolean isChunked() {
+            return true;
+        }
+    }
+
     /**
      * A ByteArrayOutputStream that can be turned into an input stream without copying the underlying buffer.
      */

client/rest/src/main/java/org/opensearch/client/RestClientBuilder.java

@@ -240,7 +240,7 @@ public RestClientBuilder setCompressionEnabled(boolean compressionEnabled) {
     }
 
     /**
-     * Whether the REST client should use Transfer-Encoding: chunked for compress requests"
+     * Whether the REST client should use Transfer-Encoding: chunked for requests or not"
      *
      * @param chunkedTransferEncodingEnabled flag for enabling Transfer-Encoding: chunked
      */