delete AsyncUtil

Author: Wenqi Li

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterAsyncSnapshot.java

@@ -27,7 +27,6 @@
 import org.apache.hadoop.hdfs.server.federation.resolver.FederationNamespaceInfo;
 import org.apache.hadoop.hdfs.server.federation.resolver.RemoteLocation;
 import org.apache.hadoop.hdfs.server.federation.router.async.ApplyFunction;
-import org.apache.hadoop.hdfs.server.federation.router.async.AsyncUtil;
 import org.apache.hadoop.hdfs.server.namenode.NameNode;
 
 import java.io.IOException;
@@ -87,7 +86,7 @@ public String createSnapshot(String snapshotRoot, String snapshotName) throws IO
           return invokedResult.replaceFirst(loc.getDest(), loc.getSrc());
         });
     }
-    return AsyncUtil.asyncReturn(String.class);
+    return asyncReturn(String.class);
   }
 
   @Override
@@ -101,7 +100,7 @@ public SnapshottableDirectoryStatus[] getSnapshottableDirListing() throws IOExce
     asyncApply((ApplyFunction<Map<FederationNamespaceInfo, SnapshottableDirectoryStatus[]>,
         SnapshottableDirectoryStatus[]>)
         ret -> RouterRpcServer.merge(ret, SnapshottableDirectoryStatus.class));
-    return AsyncUtil.asyncReturn(SnapshottableDirectoryStatus[].class);
+    return asyncReturn(SnapshottableDirectoryStatus[].class);
   }
 
   @Override