dr-elephant start error when use hdfs federation

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The following error was reported at startup,when use 'bin/start.sh app-conf/' ,and my hdfs is federation. but Normal startup when use Non-Federation

`Exception in thread "main" java.lang.ExceptionInInitializerError
at Global.onStart(Global.java:41)
at play.core.j.JavaGlobalSettingsAdapter.onStart(JavaGlobalSettingsAdapter.scala:18)
at play.api.GlobalPlugin.onStart(GlobalSettings.scala:203)
at play.api.Play$$anonfun$start$1$$anonfun$apply$mcV$sp$1.apply(Play.scala:88)
at play.api.Play$$anonfun$start$1$$anonfun$apply$mcV$sp$1.apply(Play.scala:88)
at scala.collection.immutable.List.foreach(List.scala:318)
at play.api.Play$$anonfun$start$1.apply$mcV$sp(Play.scala:88)
at play.api.Play$$anonfun$start$1.apply(Play.scala:88)
at play.api.Play$$anonfun$start$1.apply(Play.scala:88)
at play.utils.Threads$.withContextClassLoader(Threads.scala:18)
at play.api.Play$.start(Play.scala:87)
at play.core.StaticApplication.(ApplicationProvider.scala:52)
at play.core.server.NettyServer$.createServer(NettyServer.scala:243)
at play.core.server.NettyServer$$anonfun$main$3.apply(NettyServer.scala:279)
at play.core.server.NettyServer$$anonfun$main$3.apply(NettyServer.scala:274)
at scala.Option.map(Option.scala:145)
at play.core.server.NettyServer$.main(NettyServer.scala:274)
at play.core.server.NettyServer.main(NettyServer.scala)`
`Caused by: org.apache.hadoop.fs.viewfs.NotInMountpointException: getDefaultBlockSize on path ‘/' is not within a mount point
at org.apache.hadoop.fs.viewfs.ViewFileSystem$InternalDirOfViewFs.getDefaultBlockSize(ViewFileSystem.java:1006)
at org.apache.hadoop.fs.viewfs.ViewFileSystem.getDefaultBlockSize(ViewFileSystem.java:699)
at com.linkedin.drelephant.analysis.HDFSContext.load(HDFSContext.java:44)
at com.linkedin.drelephant.DrElephant.(DrElephant.java:42)
at com.linkedin.drelephant.DrElephant.(DrElephant.java:33)
... 18 more`

Reproduce the failure with bin/start.sh app-conf/ against a federated HDFS setup, then trace startup through Global.onStart and DrElephant initialization. Inspect HDFSContext.load in HDFSContext.java at line 44 and the reported ViewFileSystem exception. Done means startup succeeds with HDFS federation while retaining normal non-federated startup.

Written by the indexing model from the issue text.