YARN-11435. Fix CheckStyle.

Author: slfan1989

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-common/src/main/java/org/apache/hadoop/yarn/server/federation/utils/FederationStateStoreFacade.java

@@ -105,7 +105,7 @@ public final class FederationStateStoreFacade {
   private static final Logger LOG =
       LoggerFactory.getLogger(FederationStateStoreFacade.class);
 
-  private static FederationStateStoreFacade FACADE;
+  private static FederationStateStoreFacade facade;
 
   private static Random rand = new Random(System.currentTimeMillis());
 
@@ -194,22 +194,23 @@ public static RetryPolicy createRetryPolicy(Configuration conf) {
 
   /**
    * Returns the singleton instance of the FederationStateStoreFacade object.
+   * @param conf Configuration.
    *
    * @return the singleton {@link FederationStateStoreFacade} instance
    */
   public static FederationStateStoreFacade getInstance(Configuration conf) {
-    if(FACADE == null) {
+    if(facade == null) {
       synchronized (FederationStateStoreFacade.class) {
-        if (FACADE == null) {
+        if (facade == null) {
           Configuration yarnConf = new Configuration();
-          if (conf == null) {
+          if (conf != null) {
             yarnConf = conf;
           }
-          FACADE = new FederationStateStoreFacade(yarnConf);
+          facade = new FederationStateStoreFacade(yarnConf);
         }
       }
     }
-    return FACADE;
+    return facade;
   }
 
   /**