Compile fix + removed couple of unused imports

Author: gaborgsomogyi

core/src/test/scala/org/apache/spark/deploy/security/HadoopDelegationTokenManagerSuite.scala

@@ -18,7 +18,6 @@
 package org.apache.spark.deploy.security
 
 import org.apache.hadoop.conf.Configuration
-import org.apache.hadoop.fs.FileSystem
 import org.apache.hadoop.security.Credentials
 
 import org.apache.spark.{SparkConf, SparkFunSuite}

external/kafka-0-10-token-provider/src/main/scala/org/apache/spark/kafka010/KafkaDelegationTokenProvider.scala

@@ -21,7 +21,6 @@ import scala.language.existentials
 import scala.util.control.NonFatal
 
 import org.apache.hadoop.conf.Configuration
-import org.apache.hadoop.fs.FileSystem
 import org.apache.hadoop.security.Credentials
 import org.apache.kafka.common.security.auth.SecurityProtocol.{SASL_PLAINTEXT, SASL_SSL, SSL}
 

sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLCLIDriver.scala

@@ -126,7 +126,7 @@ private[hive] object SparkSQLCLIDriver extends Logging {
     val tokenProvider = new HiveDelegationTokenProvider()
     if (tokenProvider.delegationTokensRequired(sparkConf, hadoopConf)) {
       val credentials = new Credentials()
-      tokenProvider.obtainDelegationTokens(hadoopConf, sparkConf, Set.empty, credentials)
+      tokenProvider.obtainDelegationTokens(hadoopConf, sparkConf, credentials)
       UserGroupInformation.getCurrentUser.addCredentials(credentials)
     }