diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/main/java/org/apache/hadoop/yarn/server/router/clientrm/FederationClientInterceptor.java b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/main/java/org/apache/hadoop/yarn/server/router/clientrm/FederationClientInterceptor.java
index 391bc1ca98..3133ad5ced 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/main/java/org/apache/hadoop/yarn/server/router/clientrm/FederationClientInterceptor.java
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/main/java/org/apache/hadoop/yarn/server/router/clientrm/FederationClientInterceptor.java
@@ -664,11 +664,10 @@ public GetClusterMetricsResponse getClusterMetrics(
         federationFacade.getSubClusters(true);
     ClientMethod remoteMethod = new ClientMethod("getClusterMetrics",
         new Class[] {GetClusterMetricsRequest.class}, new Object[] {request});
-    ArrayList<SubClusterId> clusterList = new ArrayList<>(subclusters.keySet());
     Map<SubClusterId, GetClusterMetricsResponse> clusterMetrics;
 
     try {
-      clusterMetrics = invokeConcurrent(clusterList, remoteMethod,
+      clusterMetrics = invokeConcurrent(subclusters.keySet(), remoteMethod,
           GetClusterMetricsResponse.class);
 
     } catch (Exception ex) {