add ResponseException#status (opensearch-project#756)

this allows accessing the HTTP status code of the response when an API
returns a `ResponseException`. this was not possible through
`getResponse` since `Response` itself is package-private and thus its
members (even though they are marked as `public`) are not accessible to
external consumers.

solves opensearch-project#749

Signed-off-by: Ralph Ursprung <Ralph.Ursprung@avaloq.com>
(cherry picked from commit 863518c)

CHANGELOG.md

@@ -1,9 +1,11 @@
 # CHANGELOG
 Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
+
 ## [Unreleased 2.x]
 ### Added
 - Added support for icu_collation_keyword type ([#725](https://github.com/opensearch-project/opensearch-java/pull/725))
 - Added support for flat_object field property ([#735](https://github.com/opensearch-project/opensearch-java/pull/735))
+- Expose HTTP status code through `ResponseException#status` ([#756](https://github.com/opensearch-project/opensearch-java/pull/756))
 
 ### Dependencies
 

java-client/src/main/java/org/opensearch/client/transport/httpclient5/ResponseException.java

@@ -64,7 +64,7 @@ static String buildMessage(Response response) throws IOException {
             response.getRequestLine().getMethod(),
             response.getHost(),
             response.getRequestLine().getUri(),
-            response.getStatusLine().toString()
+            response.getStatusLine()
         );
 
         if (response.hasWarnings()) {
@@ -92,4 +92,11 @@ static String buildMessage(Response response) throws IOException {
     public Response getResponse() {
         return response;
     }
+
+    /**
+     * HTTP status code returned by OpenSearch.
+     */
+    public int status() {
+        return this.response.getStatusLine().getStatusCode();
+    }
 }

java-client/src/test/java/org/opensearch/client/transport/httpclient5/ResponseExceptionTest.java

@@ -0,0 +1,34 @@
+package org.opensearch.client.transport.httpclient5;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.equalTo;
+
+import java.io.IOException;
+import org.apache.hc.core5.http.HttpHost;
+import org.apache.hc.core5.http.HttpStatus;
+import org.apache.hc.core5.http.HttpVersion;
+import org.apache.hc.core5.http.message.BasicClassicHttpResponse;
+import org.apache.hc.core5.http.message.RequestLine;
+import org.junit.Test;
+
+public class ResponseExceptionTest {
+
+    @Test
+    public void testStatus() throws IOException {
+        final var response = this.buildResponseException(HttpStatus.SC_BAD_REQUEST);
+        assertThat(response.status(), equalTo(HttpStatus.SC_BAD_REQUEST));
+    }
+
+    private ResponseException buildResponseException(final int statusCode) throws IOException {
+        return new ResponseException(this.buildTestResponse(statusCode));
+    }
+
+    private Response buildTestResponse(final int statusCode) {
+        return new Response(
+            new RequestLine("GET", "/", HttpVersion.HTTP_1_1),
+            new HttpHost("localhost"),
+            new BasicClassicHttpResponse(statusCode)
+        );
+    }
+
+}