[SPARK-19227][SPARK-19251] remove unused imports and outdated comments

## What changes were proposed in this pull request?
remove ununsed imports and outdated comments, and fix some minor code style issue.

## How was this patch tested?
existing ut

Author: uncleGen <hustyugm@gmail.com>

Closes #16591 from uncleGen/SPARK-19227.

core/src/main/scala/org/apache/spark/SecurityManager.scala

@@ -26,11 +26,9 @@ import javax.net.ssl._
 import com.google.common.hash.HashCodes
 import com.google.common.io.Files
 import org.apache.hadoop.io.Text
-import org.apache.hadoop.security.Credentials
 
 import org.apache.spark.deploy.SparkHadoopUtil
 import org.apache.spark.internal.Logging
-import org.apache.spark.internal.config._
 import org.apache.spark.network.sasl.SecretKeyHolder
 import org.apache.spark.util.Utils
 

core/src/main/scala/org/apache/spark/SparkContext.scala

@@ -19,7 +19,7 @@ package org.apache.spark
 
 import java.io._
 import java.lang.reflect.Constructor
-import java.net.{URI}
+import java.net.URI
 import java.util.{Arrays, Locale, Properties, ServiceLoader, UUID}
 import java.util.concurrent.{ConcurrentHashMap, ConcurrentMap}
 import java.util.concurrent.atomic.{AtomicBoolean, AtomicInteger, AtomicReference}

core/src/main/scala/org/apache/spark/deploy/ExternalShuffleServiceSource.scala

@@ -19,7 +19,7 @@ package org.apache.spark.deploy
 
 import javax.annotation.concurrent.ThreadSafe
 
-import com.codahale.metrics.{Gauge, MetricRegistry}
+import com.codahale.metrics.MetricRegistry
 
 import org.apache.spark.metrics.source.Source
 import org.apache.spark.network.shuffle.ExternalShuffleBlockHandler

core/src/main/scala/org/apache/spark/deploy/SparkSubmit.scala

@@ -17,7 +17,7 @@
 
 package org.apache.spark.deploy
 
-import java.io.{File, IOException, PrintStream}
+import java.io.{File, IOException}
 import java.lang.reflect.{InvocationTargetException, Modifier, UndeclaredThrowableException}
 import java.net.URL
 import java.security.PrivilegedExceptionAction

core/src/main/scala/org/apache/spark/deploy/worker/ui/LogPage.scala

@@ -22,8 +22,6 @@ import javax.servlet.http.HttpServletRequest
 
 import scala.xml.{Node, Unparsed}
 
-import com.google.common.cache.{CacheBuilder, CacheLoader, LoadingCache}
-
 import org.apache.spark.internal.Logging
 import org.apache.spark.ui.{UIUtils, WebUIPage}
 import org.apache.spark.util.Utils

core/src/main/scala/org/apache/spark/internal/config/ConfigEntry.scala

@@ -17,12 +17,6 @@
 
 package org.apache.spark.internal.config
 
-import java.util.{Map => JMap}
-
-import scala.util.matching.Regex
-
-import org.apache.spark.SparkConf
-
 /**
  * An entry contains all meta information for a configuration.
  *
@@ -34,7 +28,6 @@ import org.apache.spark.SparkConf
  * value declared as a string.
  *
  * @param key the key for the configuration
- * @param defaultValue the default value for the configuration
  * @param valueConverter how to convert a string to the value. It should throw an exception if the
  *                       string does not have the required format.
  * @param stringConverter how to convert a value to a string that the user can use it as a valid
@@ -76,7 +69,7 @@ private class ConfigEntryWithDefault[T] (
     stringConverter: T => String,
     doc: String,
     isPublic: Boolean)
-    extends ConfigEntry(key, valueConverter, stringConverter, doc, isPublic) {
+  extends ConfigEntry(key, valueConverter, stringConverter, doc, isPublic) {
 
   override def defaultValue: Option[T] = Some(_defaultValue)
 
@@ -95,7 +88,7 @@ private class ConfigEntryWithDefaultString[T] (
     stringConverter: T => String,
     doc: String,
     isPublic: Boolean)
-    extends ConfigEntry(key, valueConverter, stringConverter, doc, isPublic) {
+  extends ConfigEntry(key, valueConverter, stringConverter, doc, isPublic) {
 
   override def defaultValue: Option[T] = Some(valueConverter(_defaultValue))
 
@@ -118,8 +111,8 @@ private[spark] class OptionalConfigEntry[T](
     val rawStringConverter: T => String,
     doc: String,
     isPublic: Boolean)
-    extends ConfigEntry[Option[T]](key, s => Some(rawValueConverter(s)),
+  extends ConfigEntry[Option[T]](key, s => Some(rawValueConverter(s)),
-      v => v.map(rawStringConverter).orNull, doc, isPublic) {
+    v => v.map(rawStringConverter).orNull, doc, isPublic) {
 
   override def defaultValueString: String = "<undefined>"
 
@@ -137,7 +130,7 @@ private class FallbackConfigEntry[T] (
     doc: String,
     isPublic: Boolean,
     private[config] val fallback: ConfigEntry[T])
-    extends ConfigEntry[T](key, fallback.valueConverter, fallback.stringConverter, doc, isPublic) {
+  extends ConfigEntry[T](key, fallback.valueConverter, fallback.stringConverter, doc, isPublic) {
 
   override def defaultValueString: String = s"<value of ${fallback.key}>"
 

core/src/main/scala/org/apache/spark/internal/config/ConfigReader.scala

@@ -18,7 +18,6 @@
 package org.apache.spark.internal.config
 
 import java.util.{Map => JMap}
-import java.util.regex.Pattern
 
 import scala.collection.mutable.HashMap
 import scala.util.matching.Regex

core/src/main/scala/org/apache/spark/rpc/RpcTimeout.scala

@@ -19,11 +19,10 @@ package org.apache.spark.rpc
 
 import java.util.concurrent.TimeoutException
 
-import scala.concurrent.{Await, Future}
+import scala.concurrent.Future
 import scala.concurrent.duration._
-import scala.util.control.NonFatal
 
-import org.apache.spark.{SparkConf, SparkException}
+import org.apache.spark.SparkConf
 import org.apache.spark.util.{ThreadUtils, Utils}
 
 /**

core/src/main/scala/org/apache/spark/scheduler/ResultTask.scala

@@ -24,7 +24,6 @@ import java.util.Properties
 
 import org.apache.spark._
 import org.apache.spark.broadcast.Broadcast
-import org.apache.spark.executor.TaskMetrics
 import org.apache.spark.rdd.RDD
 
 /**

core/src/main/scala/org/apache/spark/scheduler/ShuffleMapTask.scala

@@ -25,7 +25,6 @@ import scala.language.existentials
 
 import org.apache.spark._
 import org.apache.spark.broadcast.Broadcast
-import org.apache.spark.executor.TaskMetrics
 import org.apache.spark.internal.Logging
 import org.apache.spark.rdd.RDD
 import org.apache.spark.shuffle.ShuffleWriter

core/src/main/scala/org/apache/spark/scheduler/Stage.scala

@@ -19,7 +19,6 @@ package org.apache.spark.scheduler
 
 import scala.collection.mutable.HashSet
 
-import org.apache.spark._
 import org.apache.spark.executor.TaskMetrics
 import org.apache.spark.internal.Logging
 import org.apache.spark.rdd.RDD

core/src/main/scala/org/apache/spark/scheduler/Task.scala

@@ -46,7 +46,6 @@ import org.apache.spark.util._
  * @param stageId id of the stage this task belongs to
  * @param stageAttemptId attempt id of the stage this task belongs to
  * @param partitionId index of the number in the RDD
- * @param metrics a `TaskMetrics` that is created at driver side and sent to executor side.
  * @param localProperties copy of thread-local properties set by the user on the driver side.
  * @param serializedTaskMetrics a `TaskMetrics` that is created and serialized on the driver side
  *                              and sent to executor side.

core/src/main/scala/org/apache/spark/serializer/Serializer.scala

@@ -23,7 +23,6 @@ import javax.annotation.concurrent.NotThreadSafe
 
 import scala.reflect.ClassTag
 
-import org.apache.spark.SparkEnv
 import org.apache.spark.annotation.{DeveloperApi, Private}
 import org.apache.spark.util.NextIterator
 

core/src/main/scala/org/apache/spark/serializer/SerializerManager.scala

@@ -23,7 +23,6 @@ import java.nio.ByteBuffer
 import scala.reflect.ClassTag
 
 import org.apache.spark.SparkConf
-import org.apache.spark.internal.config._
 import org.apache.spark.io.CompressionCodec
 import org.apache.spark.security.CryptoStreamUtils
 import org.apache.spark.storage._

core/src/main/scala/org/apache/spark/status/api/v1/ExecutorListResource.scala

@@ -16,7 +16,7 @@
 */
 package org.apache.spark.status.api.v1
 
-import javax.ws.rs.{GET, PathParam, Produces}
+import javax.ws.rs.{GET, Produces}
 import javax.ws.rs.core.MediaType
 
 import org.apache.spark.ui.SparkUI

core/src/main/scala/org/apache/spark/storage/StorageLevel.scala

@@ -31,7 +31,7 @@ import org.apache.spark.util.Utils
  * ExternalBlockStore, whether to keep the data in memory in a serialized format, and whether
  * to replicate the RDD partitions on multiple nodes.
  *
- * The [[org.apache.spark.storage.StorageLevel$]] singleton object contains some static constants
+ * The [[org.apache.spark.storage.StorageLevel]] singleton object contains some static constants
  * for commonly useful storage levels. To create your own storage level object, use the
  * factory method of the singleton object (`StorageLevel(...)`).
  */

core/src/main/scala/org/apache/spark/util/random/RandomSampler.scala

@@ -19,7 +19,6 @@ package org.apache.spark.util.random
 
 import java.util.Random
 
-import scala.collection.mutable.ArrayBuffer
 import scala.reflect.ClassTag
 
 import org.apache.commons.math3.distribution.PoissonDistribution

core/src/test/scala/org/apache/spark/InternalAccumulatorSuite.scala

@@ -17,7 +17,6 @@
 
 package org.apache.spark
 
-import scala.collection.JavaConverters._
 import scala.collection.mutable.ArrayBuffer
 
 import org.apache.spark.executor.TaskMetrics

core/src/test/scala/org/apache/spark/network/netty/NettyBlockTransferServiceSuite.scala

@@ -23,7 +23,6 @@ import org.mockito.Mockito.mock
 import org.scalatest._
 
 import org.apache.spark.{SecurityManager, SparkConf, SparkFunSuite}
-import org.apache.spark.internal.config._
 import org.apache.spark.network.BlockDataManager
 
 class NettyBlockTransferServiceSuite

core/src/test/scala/org/apache/spark/util/DistributionSuite.scala

@@ -21,10 +21,6 @@ import org.scalatest.Matchers
 
 import org.apache.spark.SparkFunSuite
 
-/**
- *
- */
-
 class DistributionSuite extends SparkFunSuite with Matchers {
   test("summary") {
     val d = new Distribution((1 to 100).toArray.map{_.toDouble})

examples/src/main/scala/org/apache/spark/examples/ml/BinarizerExample.scala

@@ -21,7 +21,7 @@ package org.apache.spark.examples.ml
 // $example on$
 import org.apache.spark.ml.feature.Binarizer
 // $example off$
-import org.apache.spark.sql.{SparkSession}
+import org.apache.spark.sql.SparkSession
 
 object BinarizerExample {
   def main(args: Array[String]): Unit = {

examples/src/main/scala/org/apache/spark/examples/sql/SparkSQLExample.scala

@@ -16,10 +16,6 @@
  */
 package org.apache.spark.examples.sql
 
-// $example on:schema_inferring$
-import org.apache.spark.sql.catalyst.encoders.ExpressionEncoder
-import org.apache.spark.sql.Encoder
-// $example off:schema_inferring$
 import org.apache.spark.sql.Row
 // $example on:init_session$
 import org.apache.spark.sql.SparkSession

examples/src/main/scala/org/apache/spark/examples/sql/streaming/StructuredNetworkWordCount.scala

@@ -18,7 +18,6 @@
 // scalastyle:off println
 package org.apache.spark.examples.sql.streaming
 
-import org.apache.spark.sql.functions._
 import org.apache.spark.sql.SparkSession
 
 /**

external/kafka-0-10-sql/src/main/scala/org/apache/spark/sql/kafka010/KafkaSource.scala

@@ -24,7 +24,7 @@ import java.nio.charset.StandardCharsets
 import scala.collection.JavaConverters._
 import scala.util.control.NonFatal
 
-import org.apache.kafka.clients.consumer.{Consumer, ConsumerConfig, KafkaConsumer, OffsetOutOfRangeException}
+import org.apache.kafka.clients.consumer.{Consumer, ConsumerConfig, KafkaConsumer}
 import org.apache.kafka.clients.consumer.internals.NoOpConsumerRebalanceListener
 import org.apache.kafka.common.TopicPartition
 

external/kafka-0-10/src/main/scala/org/apache/spark/streaming/kafka010/KafkaRDD.scala

@@ -24,7 +24,7 @@ import scala.collection.mutable.ArrayBuffer
 import org.apache.kafka.clients.consumer.{ ConsumerConfig, ConsumerRecord }
 import org.apache.kafka.common.TopicPartition
 
-import org.apache.spark.{Partition, SparkContext, SparkException, TaskContext}
+import org.apache.spark.{Partition, SparkContext, TaskContext}
 import org.apache.spark.internal.Logging
 import org.apache.spark.partial.{BoundedDouble, PartialResult}
 import org.apache.spark.rdd.RDD

external/kafka-0-10/src/main/scala/org/apache/spark/streaming/kafka010/KafkaUtils.scala

@@ -25,7 +25,6 @@ import org.apache.kafka.common.TopicPartition
 import org.apache.spark.SparkContext
 import org.apache.spark.annotation.Experimental
 import org.apache.spark.api.java.{ JavaRDD, JavaSparkContext }
-import org.apache.spark.api.java.function.{ Function0 => JFunction0 }
 import org.apache.spark.internal.Logging
 import org.apache.spark.rdd.RDD
 import org.apache.spark.streaming.StreamingContext

external/kinesis-asl/src/main/scala/org/apache/spark/examples/streaming/KinesisWordCountASL.scala

@@ -22,7 +22,7 @@ import java.nio.ByteBuffer
 
 import scala.util.Random
 
-import com.amazonaws.auth.{BasicAWSCredentials, DefaultAWSCredentialsProviderChain}
+import com.amazonaws.auth.DefaultAWSCredentialsProviderChain
 import com.amazonaws.regions.RegionUtils
 import com.amazonaws.services.kinesis.AmazonKinesisClient
 import com.amazonaws.services.kinesis.clientlibrary.lib.worker.InitialPositionInStream

external/kinesis-asl/src/main/scala/org/apache/spark/streaming/kinesis/KinesisCheckpointer.scala

@@ -26,7 +26,7 @@ import com.amazonaws.services.kinesis.clientlibrary.types.ShutdownReason
 import org.apache.spark.internal.Logging
 import org.apache.spark.streaming.Duration
 import org.apache.spark.streaming.util.RecurringTimer
-import org.apache.spark.util.{Clock, SystemClock, ThreadUtils}
+import org.apache.spark.util.{Clock, SystemClock}
 
 /**
  * This is a helper class for managing Kinesis checkpointing.

external/kinesis-asl/src/test/scala/org/apache/spark/streaming/kinesis/KinesisCheckpointerSuite.scala

@@ -17,7 +17,7 @@
 
 package org.apache.spark.streaming.kinesis
 
-import java.util.concurrent.{ExecutorService, TimeoutException}
+import java.util.concurrent.TimeoutException
 
 import scala.concurrent.{Await, ExecutionContext, Future}
 import scala.concurrent.duration._
@@ -30,7 +30,6 @@ import org.mockito.invocation.InvocationOnMock
 import org.mockito.stubbing.Answer
 import org.scalatest.{BeforeAndAfterEach, PrivateMethodTester}
 import org.scalatest.concurrent.Eventually
-import org.scalatest.concurrent.Eventually._
 import org.scalatest.mock.MockitoSugar
 
 import org.apache.spark.streaming.{Duration, TestSuiteBase}

launcher/src/test/java/org/apache/spark/launcher/SparkSubmitOptionParserSuite.java

@@ -23,11 +23,8 @@ import java.util.List;
 
 import org.junit.Before;
 import org.junit.Test;
-import static org.junit.Assert.*;
 import static org.mockito.Mockito.*;
 
-import static org.apache.spark.launcher.SparkSubmitOptionParser.*;
-
 public class SparkSubmitOptionParserSuite extends BaseSuite {
 
   private SparkSubmitOptionParser parser;

mllib/src/main/scala/org/apache/spark/ml/classification/Classifier.scala

@@ -27,7 +27,7 @@ import org.apache.spark.ml.util.{MetadataUtils, SchemaUtils}
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.{DataFrame, Dataset, Row}
 import org.apache.spark.sql.functions._
-import org.apache.spark.sql.types.{DataType, DoubleType, StructType}
+import org.apache.spark.sql.types.{DataType, StructType}
 
 /**
  * (private[spark]) Params for classification.

mllib/src/main/scala/org/apache/spark/ml/classification/GBTClassifier.scala

@@ -37,7 +37,6 @@ import org.apache.spark.mllib.tree.model.{GradientBoostedTreesModel => OldGBTMod
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.{DataFrame, Dataset, Row}
 import org.apache.spark.sql.functions._
-import org.apache.spark.sql.types.DoubleType
 
 /**
  * Gradient-Boosted Trees (GBTs) (http://en.wikipedia.org/wiki/Gradient_boosting)

mllib/src/main/scala/org/apache/spark/ml/source/libsvm/LibSVMRelation.scala

@@ -25,7 +25,7 @@ import org.apache.hadoop.mapreduce.{Job, TaskAttemptContext}
 
 import org.apache.spark.TaskContext
 import org.apache.spark.ml.feature.LabeledPoint
-import org.apache.spark.ml.linalg.{Vector, Vectors, VectorUDT}
+import org.apache.spark.ml.linalg.{Vectors, VectorUDT}
 import org.apache.spark.mllib.util.MLUtils
 import org.apache.spark.sql.{Row, SparkSession}
 import org.apache.spark.sql.catalyst.InternalRow

repl/scala-2.10/src/main/scala/org/apache/spark/repl/SparkCommandLine.scala

@@ -17,8 +17,8 @@
 
 package org.apache.spark.repl
 
-import scala.tools.nsc.{Settings, CompilerCommand}
+import scala.tools.nsc.{CompilerCommand, Settings}
-import scala.Predef._
+
 import org.apache.spark.annotation.DeveloperApi
 
 /**

repl/scala-2.10/src/main/scala/org/apache/spark/repl/SparkILoopInit.scala

@@ -10,8 +10,6 @@ package org.apache.spark.repl
 import scala.tools.nsc._
 import scala.tools.nsc.interpreter._
 
-import scala.reflect.internal.util.Position
-import scala.util.control.Exception.ignoring
 import scala.tools.nsc.util.stackTraceString
 
 import org.apache.spark.SPARK_VERSION

resource-managers/yarn/src/main/scala/org/apache/spark/deploy/yarn/ApplicationMasterArguments.scala

@@ -19,8 +19,6 @@ package org.apache.spark.deploy.yarn
 
 import scala.collection.mutable.ArrayBuffer
 
-import org.apache.spark.util.{IntParam, MemoryParam}
-
 class ApplicationMasterArguments(val args: Array[String]) {
   var userJar: String = null
   var userClass: String = null

resource-managers/yarn/src/test/scala/org/apache/spark/deploy/yarn/security/HadoopFSCredentialProviderSuite.scala

@@ -18,10 +18,9 @@
 package org.apache.spark.deploy.yarn.security
 
 import org.apache.hadoop.conf.Configuration
-import org.apache.hadoop.fs.Path
 import org.scalatest.{Matchers, PrivateMethodTester}
 
-import org.apache.spark.{SparkConf, SparkException, SparkFunSuite}
+import org.apache.spark.{SparkException, SparkFunSuite}
 
 class HadoopFSCredentialProviderSuite
     extends SparkFunSuite

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/MonotonicallyIncreasingID.scala

@@ -17,7 +17,6 @@
 
 package org.apache.spark.sql.catalyst.expressions
 
-import org.apache.spark.TaskContext
 import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.catalyst.expressions.codegen.{CodegenContext, ExprCode}
 import org.apache.spark.sql.types.{DataType, LongType}

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/ApproximatePercentile.scala

@@ -21,7 +21,6 @@ import java.nio.ByteBuffer
 
 import com.google.common.primitives.{Doubles, Ints, Longs}
 
-import org.apache.spark.sql.AnalysisException
 import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.catalyst.analysis.TypeCheckResult
 import org.apache.spark.sql.catalyst.analysis.TypeCheckResult.{TypeCheckFailure, TypeCheckSuccess}

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/Percentile.scala

@@ -20,7 +20,6 @@ package org.apache.spark.sql.catalyst.expressions.aggregate
 import java.io.{ByteArrayInputStream, ByteArrayOutputStream, DataInputStream, DataOutputStream}
 import java.util
 
-import org.apache.spark.sql.AnalysisException
 import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.catalyst.analysis.TypeCheckResult
 import org.apache.spark.sql.catalyst.analysis.TypeCheckResult.{TypeCheckFailure, TypeCheckSuccess}

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/aggregate/collect.scala

@@ -17,8 +17,6 @@
 
 package org.apache.spark.sql.catalyst.expressions.aggregate
 
-import java.io.{ByteArrayInputStream, ByteArrayOutputStream, DataInputStream, DataOutputStream}
-
 import scala.collection.generic.Growable
 import scala.collection.mutable
 

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/jsonExpressions.scala

@@ -23,7 +23,6 @@ import scala.util.parsing.combinator.RegexParsers
 
 import com.fasterxml.jackson.core._
 
-import org.apache.spark.sql.AnalysisException
 import org.apache.spark.sql.catalyst.analysis.TypeCheckResult
 import org.apache.spark.sql.catalyst.expressions.codegen.CodegenFallback
 import org.apache.spark.sql.catalyst.InternalRow

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/nullExpressions.scala

@@ -18,7 +18,7 @@
 package org.apache.spark.sql.catalyst.expressions
 
 import org.apache.spark.sql.catalyst.InternalRow
-import org.apache.spark.sql.catalyst.analysis.{TypeCheckResult, TypeCoercion}
+import org.apache.spark.sql.catalyst.analysis.TypeCheckResult
 import org.apache.spark.sql.catalyst.expressions.codegen.{CodegenContext, ExprCode}
 import org.apache.spark.sql.catalyst.util.TypeUtils
 import org.apache.spark.sql.types._

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/planning/patterns.scala

@@ -17,15 +17,11 @@
 
 package org.apache.spark.sql.catalyst.planning
 
-import scala.annotation.tailrec
-import scala.collection.mutable
-
 import org.apache.spark.internal.Logging
 import org.apache.spark.sql.catalyst.expressions._
 import org.apache.spark.sql.catalyst.expressions.aggregate.AggregateExpression
 import org.apache.spark.sql.catalyst.plans._
 import org.apache.spark.sql.catalyst.plans.logical._
-import org.apache.spark.sql.types.IntegerType
 
 /**
  * A pattern that matches any number of project or filter operations on top of another relational

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/joinTypes.scala

@@ -17,7 +17,6 @@
 
 package org.apache.spark.sql.catalyst.plans
 
-import org.apache.spark.sql.catalyst.analysis.UnresolvedAttribute
 import org.apache.spark.sql.catalyst.expressions.Attribute
 
 object JoinType {

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/EventTimeWatermark.scala

@@ -17,7 +17,7 @@
 
 package org.apache.spark.sql.catalyst.plans.logical
 
-import org.apache.spark.sql.catalyst.expressions.{Attribute, Expression}
+import org.apache.spark.sql.catalyst.expressions.Attribute
 import org.apache.spark.sql.types.MetadataBuilder
 import org.apache.spark.unsafe.types.CalendarInterval
 

sql/hive/src/main/scala/org/apache/spark/sql/hive/MetastoreRelation.scala

@@ -36,7 +36,6 @@ import org.apache.spark.sql.catalyst.catalog._
 import org.apache.spark.sql.catalyst.expressions.{AttributeMap, AttributeReference, Expression}
 import org.apache.spark.sql.catalyst.plans.logical.{LeafNode, LogicalPlan, Statistics}
 import org.apache.spark.sql.execution.FileRelation
-import org.apache.spark.sql.hive.client.HiveClient
 import org.apache.spark.sql.types.StructField