Adding number of routing shards to index settings before passing into GetSettingsResponse

Author: Sophia

server/src/main/java/org/opensearch/action/admin/indices/settings/get/TransportGetSettingsAction.java

@@ -130,6 +130,11 @@ protected void clusterManagerOperation(GetSettingsRequest request, ClusterState
                 indexSettings = indexSettings.filter(k -> Regex.simpleMatch(request.names(), k));
             }
 
+            indexSettings = Settings.builder()
+                .put(indexSettings)
+                .put(IndexMetadata.INDEX_NUMBER_OF_ROUTING_SHARDS_SETTING.getKey(), indexMetadata.getRoutingNumShards())
+                .build();
+
             indexToSettingsBuilder.put(concreteIndex.getName(), indexSettings);
             if (request.includeDefaults()) {
                 Settings defaultSettings = settingsFilter.filter(indexScopedSettings.diff(indexSettings, Settings.EMPTY));