fix unit test.

Author: hfutatzhanghb

hadoop-hdfs-project/hadoop-hdfs-rbf/src/test/java/org/apache/hadoop/hdfs/server/federation/router/async/TestRouterAsyncRPCMultipleDestinationMountTableResolver.java

@@ -137,7 +137,8 @@ public void testIsMultiDestDir() throws Exception {
     assertFalse(syncReturn(boolean.class));
     routerFs.createSymlink(new Path("/mount/dir/file"),
         new Path("/mount/dir/link"), true);
-    assertFalse(client.isMultiDestDirectory("/mount/dir/link"));
+    client.isMultiDestDirectory("/mount/dir/link");
+    assertFalse(syncReturn(boolean.class));
     routerFs.createSymlink(new Path("/mount/dir/dir"),
         new Path("/mount/dir/linkDir"), true);
     client.isMultiDestDirectory("/mount/dir/linkDir");