Respects the routing field in TermVectorsRequest in the REST client

CHANGELOG.md

@@ -39,6 +39,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Fix QueryPhaseResultConsumer incomplete callback loops ([#19231](https://github.com/opensearch-project/OpenSearch/pull/19231))
 - Fix the `scaled_float` precision issue ([#19188](https://github.com/opensearch-project/OpenSearch/pull/19188))
 - Fix Using an excessively large reindex slice can lead to a JVM OutOfMemoryError on coordinator.([#18964](https://github.com/opensearch-project/OpenSearch/pull/18964))
+- Serialize routing field in TermVectorsRequest in the REST client ([#19195](https://github.com/opensearch-project/OpenSearch/pull/19195))
 
 ### Dependencies
 - Bump `com.netflix.nebula.ospackage-base` from 12.0.0 to 12.1.0 ([#19019](https://github.com/opensearch-project/OpenSearch/pull/19019))

client/rest-high-level/src/main/java/org/opensearch/client/core/TermVectorsRequest.java

@@ -278,6 +278,7 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
         if (requestFieldStatistics == false) builder.field("field_statistics", false);
         if (requestTermStatistics) builder.field("term_statistics", true);
         if (perFieldAnalyzer != null) builder.field("per_field_analyzer", perFieldAnalyzer);
+        if (routing != null) builder.field("routing", routing);
 
         if (docBuilder != null) {
             BytesReference doc = BytesReference.bytes(docBuilder);

client/rest-high-level/src/test/java/org/opensearch/client/core/TermVectorsRequestTests.java

@@ -0,0 +1,40 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+package org.opensearch.client.core;
+
+import org.opensearch.client.AbstractRequestTestCase;
+import org.opensearch.core.xcontent.XContentParser;
+
+import java.io.IOException;
+
+public class TermVectorsRequestTests extends AbstractRequestTestCase<
+    TermVectorsRequest,
+    org.opensearch.action.termvectors.TermVectorsRequest> {
+    @Override
+    protected TermVectorsRequest createClientTestInstance() {
+        TermVectorsRequest clientRequest = new TermVectorsRequest(randomAlphaOfLength(5), randomAlphaOfLength(5));
+        clientRequest.setRouting("some-routing");
+        return clientRequest;
+    }
+
+    @Override
+    protected org.opensearch.action.termvectors.TermVectorsRequest doParseToServerInstance(XContentParser parser) throws IOException {
+        org.opensearch.action.termvectors.TermVectorsRequest serverRequest = new org.opensearch.action.termvectors.TermVectorsRequest();
+        org.opensearch.action.termvectors.TermVectorsRequest.parseRequest(serverRequest, parser);
+        return serverRequest;
+    }
+
+    @Override
+    protected void assertInstances(
+        org.opensearch.action.termvectors.TermVectorsRequest serverInstance,
+        TermVectorsRequest clientTestInstance
+    ) {
+        assertEquals(serverInstance.routing(), clientTestInstance.getRouting());
+    }
+}