HDFS-17678.resolve the problem for the space balancing strategy of hadoop RBF component

Author: hanleiit

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/resolver/order/AvailableSpaceResolver.java

@@ -31,6 +31,7 @@
 import org.apache.hadoop.hdfs.server.federation.resolver.PathLocation;
 import org.apache.hadoop.hdfs.server.federation.resolver.order.AvailableSpaceResolver.SubclusterAvailableSpace;
 import org.apache.hadoop.hdfs.server.federation.router.RBFConfigKeys;
+import org.apache.hadoop.hdfs.server.federation.resolver.RemoteLocation;
 import org.apache.hadoop.hdfs.server.federation.router.Router;
 import org.apache.hadoop.hdfs.server.federation.store.MembershipStore;
 import org.apache.hadoop.hdfs.server.federation.store.protocol.GetNamenodeRegistrationsRequest;