YARN-11180. Fix CheckStyle.

Author: slfan1989

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/main/java/org/apache/hadoop/yarn/server/router/clientrm/FederationClientInterceptor.java

@@ -695,17 +695,17 @@ public GetClusterMetricsResponse getClusterMetrics(
     Map<SubClusterId, SubClusterInfo> subClusters = federationFacade.getSubClusters(true);
     ClientMethod remoteMethod = new ClientMethod("getClusterMetrics",
         new Class[] {GetClusterMetricsRequest.class}, new Object[] {request});
-    Map<SubClusterId, GetClusterMetricsResponse> clusterMetrics = null;
+    Collection<GetClusterMetricsResponse> clusterMetrics = null;
     try {
-      Set keySet = subClusters.keySet();
-      clusterMetrics = invokeConcurrent(keySet, remoteMethod, GetClusterMetricsResponse.class);
+      clusterMetrics = invokeAppClientProtocolMethod(
+          true, remoteMethod, GetClusterMetricsResponse.class);
     } catch (Exception ex) {
       routerMetrics.incrGetClusterMetricsFailedRetrieved();
       RouterServerUtil.logAndThrowException("Unable to get cluster metrics due to exception.", ex);
     }
     long stopTime = clock.getTime();
     routerMetrics.succeededGetClusterMetricsRetrieved(stopTime - startTime);
-    return RouterYarnClientUtils.merge(clusterMetrics.values());
+    return RouterYarnClientUtils.merge(clusterMetrics);
   }
 
   <R> Map<SubClusterId, R> invokeConcurrent(ArrayList<SubClusterId> clusterIds,

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/test/java/org/apache/hadoop/yarn/server/router/clientrm/TestFederationClientInterceptor.java

@@ -585,8 +585,7 @@ public void testGetClusterMetricsRequest() throws Exception {
   }
 
   /**
-   * This test validates the correctness of
-   * GetApplicationsResponse in case the
+   * This test validates the correctness of GetApplicationsResponse in case the
    * application exists in the cluster.
    */
   @Test
@@ -609,8 +608,7 @@ public void testGetApplicationsResponse()
   }
 
   /**
-   * This test validates
-   * the correctness of GetApplicationsResponse in case of
+   * This test validates the correctness of GetApplicationsResponse in case of
    * empty request.
    */
   @Test
@@ -621,8 +619,7 @@ public void testGetApplicationsNullRequest() throws Exception {
   }
 
   /**
-   * This test validates
-   * the correctness of GetApplicationsResponse in case applications
+   * This test validates the correctness of GetApplicationsResponse in case applications
    * with given type does not exist.
    */
   @Test
@@ -647,14 +644,12 @@ public void testGetApplicationsApplicationTypeNotExists() throws Exception{
   }
 
   /**
-   * This test validates
-   * the correctness of GetApplicationsResponse in case applications
+   * This test validates the correctness of GetApplicationsResponse in case applications
    * with given YarnApplicationState does not exist.
    */
   @Test
   public void testGetApplicationsApplicationStateNotExists() throws Exception {
-    LOG.info("Test FederationClientInterceptor:" +
-        " Application with state does not exist");
+    LOG.info("Test FederationClientInterceptor: Application with state does not exist.");
 
     ApplicationId appId =
         ApplicationId.newInstance(System.currentTimeMillis(), 1);
@@ -672,8 +667,7 @@ public void testGetApplicationsApplicationStateNotExists() throws Exception {
     GetApplicationsRequest requestGet =
         GetApplicationsRequest.newInstance(applicationStates);
 
-    GetApplicationsResponse responseGet =
-        interceptor.getApplications(requestGet);
+    GetApplicationsResponse responseGet = interceptor.getApplications(requestGet);
 
     Assert.assertNotNull(responseGet);
     Assert.assertTrue(responseGet.getApplicationList().isEmpty());
@@ -735,7 +729,7 @@ public void testGetQueueUserAcls() throws Exception {
     LambdaTestUtils.intercept(YarnException.class, "Missing getQueueUserAcls request.",
         () -> interceptor.getQueueUserAcls(null));
 
-    // noraml request
+    // normal request
     GetQueueUserAclsInfoResponse response = interceptor.getQueueUserAcls(
         GetQueueUserAclsInfoRequest.newInstance());