[MINOR]FsHistoryProvider import cleanup

Author: gaborgsomogyi

core/src/main/scala/org/apache/spark/deploy/history/FsHistoryProvider.scala

@@ -21,20 +21,18 @@ import java.io.{File, FileNotFoundException, IOException}
 import java.nio.file.Files
 import java.util.{Date, ServiceLoader}
 import java.util.concurrent.{ConcurrentHashMap, ExecutorService, Future, TimeUnit}
-import java.util.zip.{ZipEntry, ZipOutputStream}
+import java.util.zip.ZipOutputStream
 
 import scala.collection.JavaConverters._
 import scala.collection.mutable
 import scala.concurrent.ExecutionException
 import scala.io.Source
-import scala.util.Try
 import scala.xml.Node
 
 import com.fasterxml.jackson.annotation.JsonIgnore
-import com.google.common.io.ByteStreams
 import com.google.common.util.concurrent.MoreExecutors
 import org.apache.hadoop.fs.{FileStatus, FileSystem, Path}
-import org.apache.hadoop.hdfs.{DFSInputStream, DistributedFileSystem}
+import org.apache.hadoop.hdfs.DistributedFileSystem
 import org.apache.hadoop.hdfs.protocol.HdfsConstants
 import org.apache.hadoop.security.AccessControlException
 import org.fusesource.leveldbjni.internal.NativeDB
@@ -47,7 +45,6 @@ import org.apache.spark.internal.config.History._
 import org.apache.spark.internal.config.Status._
 import org.apache.spark.internal.config.Tests.IS_TESTING
 import org.apache.spark.internal.config.UI._
-import org.apache.spark.io.CompressionCodec
 import org.apache.spark.scheduler._
 import org.apache.spark.scheduler.ReplayListenerBus._
 import org.apache.spark.status._