Change return value of public method from ClusterManagerService to Ma…

…sterService to keep backwards compatibility

Signed-off-by: Tianli Feng <[email protected]>

server/src/main/java/org/opensearch/cluster/service/ClusterService.java

@@ -62,7 +62,7 @@
  * @opensearch.internal
  */
 public class ClusterService extends AbstractLifecycleComponent {
-    private final ClusterManagerService clusterManagerService;
+    private final MasterService clusterManagerService;
 
     private final ClusterApplierService clusterApplierService;
 
@@ -92,15 +92,15 @@ public ClusterService(Settings settings, ClusterSettings clusterSettings, Thread
         this(
             settings,
             clusterSettings,
-            new ClusterManagerService(settings, clusterSettings, threadPool),
+            new MasterService(settings, clusterSettings, threadPool),
             new ClusterApplierService(Node.NODE_NAME_SETTING.get(settings), settings, clusterSettings, threadPool)
         );
     }
 
     public ClusterService(
         Settings settings,
         ClusterSettings clusterSettings,
-        ClusterManagerService clusterManagerService,
+        MasterService clusterManagerService,
         ClusterApplierService clusterApplierService
     ) {
         this.settings = settings;
@@ -218,7 +218,7 @@ public void addLocalNodeMasterListener(LocalNodeClusterManagerListener listener)
         clusterApplierService.addLocalNodeMasterListener(listener);
     }
 
-    public ClusterManagerService getMasterService() {
+    public MasterService getMasterService() {
         return clusterManagerService;
     }