Make SearchTemplateRequest implement IndicesRequest.Replaceable (#9122)

* Make SearchTemplateRequest implement IndicesRequest.Replaceable

Signed-off-by: Craig Perkins <cwperx@amazon.com>

* Add to CHANGELOG

Signed-off-by: Craig Perkins <cwperx@amazon.com>

---------

Signed-off-by: Craig Perkins <cwperx@amazon.com>
(cherry picked from commit c73f727)
Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

CHANGELOG.md

@@ -13,6 +13,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - [distribution/archives] [Linux] [x64] Provide the variant of the distributions bundled with JRE ([#8195]()https://github.com/opensearch-project/OpenSearch/pull/8195)
 - Prioritize replica shard movement during shard relocation ([#8875](https://github.com/opensearch-project/OpenSearch/pull/8875))
 - Introducing Default and Best Compression codecs as their algorithm name ([#9123]()https://github.com/opensearch-project/OpenSearch/pull/9123)
+- Make SearchTemplateRequest implement IndicesRequest.Replaceable ([#9122]()https://github.com/opensearch-project/OpenSearch/pull/9122)
 
 ### Dependencies
 - Bump `org.apache.logging.log4j:log4j-core` from 2.17.1 to 2.20.0 ([#8307](https://github.com/opensearch-project/OpenSearch/pull/8307))

modules/lang-mustache/src/main/java/org/opensearch/script/mustache/SearchTemplateRequest.java

@@ -35,7 +35,9 @@
 import org.opensearch.action.ActionRequest;
 import org.opensearch.action.ActionRequestValidationException;
 import org.opensearch.action.CompositeIndicesRequest;
+import org.opensearch.action.IndicesRequest;
 import org.opensearch.action.search.SearchRequest;
+import org.opensearch.action.support.IndicesOptions;
 import org.opensearch.core.ParseField;
 import org.opensearch.core.common.ParsingException;
 import org.opensearch.core.common.io.stream.StreamInput;
@@ -56,7 +58,7 @@
 /**
  * A request to execute a search based on a search template.
  */
-public class SearchTemplateRequest extends ActionRequest implements CompositeIndicesRequest, ToXContentObject {
+public class SearchTemplateRequest extends ActionRequest implements IndicesRequest.Replaceable, CompositeIndicesRequest, ToXContentObject {
 
     private SearchRequest request;
     private boolean simulate = false;
@@ -254,4 +256,19 @@ public void writeTo(StreamOutput out) throws IOException {
             out.writeMap(scriptParams);
         }
     }
+
+    @Override
+    public String[] indices() {
+        return request.indices();
+    }
+
+    @Override
+    public IndicesOptions indicesOptions() {
+        return request.indicesOptions();
+    }
+
+    @Override
+    public IndicesRequest indices(String... indices) {
+        return request.indices(indices);
+    }
 }