YARN-11509. Fix CheckStyle.

Author: slfan1989

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/amrmproxy/FederationInterceptor.java

@@ -29,8 +29,14 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import java.util.concurrent.*;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ExecutorCompletionService;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
 import java.util.stream.Collectors;
+import java.util.concurrent.TimeUnit;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.io.Text;