[SPARK-13583][CORE][STREAMING] Remove unused imports and add checkstyle rule

## What changes were proposed in this pull request?

After SPARK-6990, `dev/lint-java` keeps Java code healthy and helps PR review by saving much time.
This issue aims remove unused imports from Java/Scala code and add `UnusedImports` checkstyle rule to help developers.

## How was this patch tested?
```
./dev/lint-java
./build/sbt compile
```

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #11438 from dongjoon-hyun/SPARK-13583.

34 files changed, 18 insertions, 44 deletions

diff --git a/mllib/src/main/scala/org/apache/spark/ml/classification/GBTClassifier.scala b/mllib/src/main/scala/org/apache/spark/ml/classification/GBTClassifier.scala
index 74bf07c3f1..e0ffbedf6c 100644
--- a/mllib/src/main/scala/org/apache/spark/ml/classification/GBTClassifier.scala
+++ b/mllib/src/main/scala/org/apache/spark/ml/classification/GBTClassifier.scala
@@ -24,7 +24,8 @@ import org.apache.spark.annotation.{Experimental, Since}
 import org.apache.spark.ml.{PredictionModel, Predictor}
 import org.apache.spark.ml.param.{Param, ParamMap}
 import org.apache.spark.ml.regression.DecisionTreeRegressionModel
-import org.apache.spark.ml.tree.{DecisionTreeModel, GBTParams, TreeClassifierParams, TreeEnsembleModel}
+import org.apache.spark.ml.tree.{DecisionTreeModel, GBTParams, TreeClassifierParams,
+  TreeEnsembleModel}
 import org.apache.spark.ml.util.{Identifiable, MetadataUtils}
 import org.apache.spark.mllib.linalg.Vector
 import org.apache.spark.mllib.regression.LabeledPoint
@@ -33,9 +34,8 @@ import org.apache.spark.mllib.tree.configuration.{Algo => OldAlgo}
 import org.apache.spark.mllib.tree.loss.{LogLoss => OldLogLoss, Loss => OldLoss}
 import org.apache.spark.mllib.tree.model.{GradientBoostedTreesModel => OldGBTModel}
 import org.apache.spark.rdd.RDD
-import org.apache.spark.sql.{DataFrame, Row}
+import org.apache.spark.sql.DataFrame
 import org.apache.spark.sql.functions._
-import org.apache.spark.sql.types.DoubleType
 
 /**
  * :: Experimental ::
diff --git a/mllib/src/main/scala/org/apache/spark/ml/evaluation/RegressionEvaluator.scala b/mllib/src/main/scala/org/apache/spark/ml/evaluation/RegressionEvaluator.scala
index adee61e297..9976d7ed43 100644
--- a/mllib/src/main/scala/org/apache/spark/ml/evaluation/RegressionEvaluator.scala
+++ b/mllib/src/main/scala/org/apache/spark/ml/evaluation/RegressionEvaluator.scala
@@ -20,7 +20,7 @@ package org.apache.spark.ml.evaluation
 import org.apache.spark.annotation.{Experimental, Since}
 import org.apache.spark.ml.param.{Param, ParamMap, ParamValidators}
 import org.apache.spark.ml.param.shared.{HasLabelCol, HasPredictionCol}
-import org.apache.spark.ml.util.{DefaultParamsReadable, DefaultParamsWritable, Identifiable, SchemaUtils}
+import org.apache.spark.ml.util.{DefaultParamsReadable, DefaultParamsWritable, Identifiable}
 import org.apache.spark.mllib.evaluation.RegressionMetrics
 import org.apache.spark.sql.{DataFrame, Row}
 import org.apache.spark.sql.functions._
diff --git a/mllib/src/main/scala/org/apache/spark/ml/feature/ElementwiseProduct.scala b/mllib/src/main/scala/org/apache/spark/ml/feature/ElementwiseProduct.scala
index 07a12df320..1e758cb775 100644
--- a/mllib/src/main/scala/org/apache/spark/ml/feature/ElementwiseProduct.scala
+++ b/mllib/src/main/scala/org/apache/spark/ml/feature/ElementwiseProduct.scala
@@ -19,7 +19,7 @@ package org.apache.spark.ml.feature
 
 import org.apache.spark.annotation.Experimental
 import org.apache.spark.ml.UnaryTransformer
-import org.apache.spark.ml.param.{Param, ParamMap}
+import org.apache.spark.ml.param.Param
 import org.apache.spark.ml.util.Identifiable
 import org.apache.spark.mllib.feature
 import org.apache.spark.mllib.linalg.{Vector, VectorUDT}
diff --git a/mllib/src/main/scala/org/apache/spark/ml/feature/StopWordsRemover.scala b/mllib/src/main/scala/org/apache/spark/ml/feature/StopWordsRemover.scala
index e53ef300f6..0d4c968633 100644
--- a/mllib/src/main/scala/org/apache/spark/ml/feature/StopWordsRemover.scala
+++ b/mllib/src/main/scala/org/apache/spark/ml/feature/StopWordsRemover.scala
@@ -24,7 +24,7 @@ import org.apache.spark.ml.param.shared.{HasInputCol, HasOutputCol}
 import org.apache.spark.ml.util._
 import org.apache.spark.sql.DataFrame
 import org.apache.spark.sql.functions.{col, udf}
-import org.apache.spark.sql.types.{ArrayType, StringType, StructField, StructType}
+import org.apache.spark.sql.types.{ArrayType, StringType, StructType}
 
 /**
  * stop words list
diff --git a/mllib/src/main/scala/org/apache/spark/ml/feature/Word2Vec.scala b/mllib/src/main/scala/org/apache/spark/ml/feature/Word2Vec.scala
index a4c3d2751f..3d3c7bdc2f 100644
--- a/mllib/src/main/scala/org/apache/spark/ml/feature/Word2Vec.scala
+++ b/mllib/src/main/scala/org/apache/spark/ml/feature/Word2Vec.scala
@@ -27,7 +27,7 @@ import org.apache.spark.ml.param.shared._
 import org.apache.spark.ml.util._
 import org.apache.spark.mllib.feature
 import org.apache.spark.mllib.linalg.{BLAS, Vector, Vectors, VectorUDT}
-import org.apache.spark.sql.{DataFrame, Row, SQLContext}
+import org.apache.spark.sql.{DataFrame, SQLContext}
 import org.apache.spark.sql.functions._
 import org.apache.spark.sql.types._
 
diff --git a/mllib/src/main/scala/org/apache/spark/ml/regression/GBTRegressor.scala b/mllib/src/main/scala/org/apache/spark/ml/regression/GBTRegressor.scala
index 07144cc7cf..9c842a6c88 100644
--- a/mllib/src/main/scala/org/apache/spark/ml/regression/GBTRegressor.scala
+++ b/mllib/src/main/scala/org/apache/spark/ml/regression/GBTRegressor.scala
@@ -23,18 +23,19 @@ import org.apache.spark.Logging
 import org.apache.spark.annotation.{Experimental, Since}
 import org.apache.spark.ml.{PredictionModel, Predictor}
 import org.apache.spark.ml.param.{Param, ParamMap}
-import org.apache.spark.ml.tree.{DecisionTreeModel, GBTParams, TreeEnsembleModel, TreeRegressorParams}
+import org.apache.spark.ml.tree.{DecisionTreeModel, GBTParams, TreeEnsembleModel,
+  TreeRegressorParams}
 import org.apache.spark.ml.util.{Identifiable, MetadataUtils}
 import org.apache.spark.mllib.linalg.Vector
 import org.apache.spark.mllib.regression.LabeledPoint
 import org.apache.spark.mllib.tree.{GradientBoostedTrees => OldGBT}
 import org.apache.spark.mllib.tree.configuration.{Algo => OldAlgo}
-import org.apache.spark.mllib.tree.loss.{AbsoluteError => OldAbsoluteError, Loss => OldLoss, SquaredError => OldSquaredError}
+import org.apache.spark.mllib.tree.loss.{AbsoluteError => OldAbsoluteError, Loss => OldLoss,
+  SquaredError => OldSquaredError}
 import org.apache.spark.mllib.tree.model.{GradientBoostedTreesModel => OldGBTModel}
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.DataFrame
 import org.apache.spark.sql.functions._
-import org.apache.spark.sql.types.DoubleType
 
 /**
  * :: Experimental ::
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/api/python/FPGrowthModelWrapper.scala b/mllib/src/main/scala/org/apache/spark/mllib/api/python/FPGrowthModelWrapper.scala
index ee933f4cfc..e6d1dceebe 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/api/python/FPGrowthModelWrapper.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/api/python/FPGrowthModelWrapper.scala
@@ -17,8 +17,7 @@
 
 package org.apache.spark.mllib.api.python
 
-import org.apache.spark.api.java.JavaRDD
-import org.apache.spark.mllib.fpm.{FPGrowth, FPGrowthModel}
+import org.apache.spark.mllib.fpm.FPGrowthModel
 import org.apache.spark.rdd.RDD
 
 /**
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/api/python/PythonMLLibAPI.scala b/mllib/src/main/scala/org/apache/spark/mllib/api/python/PythonMLLibAPI.scala
index cf17689a3a..886cd60687 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/api/python/PythonMLLibAPI.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/api/python/PythonMLLibAPI.scala
@@ -22,13 +22,11 @@ import java.nio.{ByteBuffer, ByteOrder}
 import java.util.{ArrayList => JArrayList, List => JList, Map => JMap}
 
 import scala.collection.JavaConverters._
-import scala.collection.mutable.ArrayBuffer
 import scala.language.existentials
 import scala.reflect.ClassTag
 
 import net.razorvine.pickle._
 
-import org.apache.spark.SparkContext
 import org.apache.spark.api.java.{JavaRDD, JavaSparkContext}
 import org.apache.spark.api.python.SerDeUtil
 import org.apache.spark.mllib.classification._
@@ -51,7 +49,8 @@ import org.apache.spark.mllib.tree.{DecisionTree, GradientBoostedTrees, RandomFo
 import org.apache.spark.mllib.tree.configuration.{Algo, BoostingStrategy, Strategy}
 import org.apache.spark.mllib.tree.impurity._
 import org.apache.spark.mllib.tree.loss.Losses
-import org.apache.spark.mllib.tree.model.{DecisionTreeModel, GradientBoostedTreesModel, RandomForestModel}
+import org.apache.spark.mllib.tree.model.{DecisionTreeModel, GradientBoostedTreesModel,
+  RandomForestModel}
 import org.apache.spark.mllib.util.{LinearDataGenerator, MLUtils}
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.{DataFrame, Row, SQLContext}
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/api/python/Word2VecModelWrapper.scala b/mllib/src/main/scala/org/apache/spark/mllib/api/python/Word2VecModelWrapper.scala
index 55dfd973eb..073f03e16f 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/api/python/Word2VecModelWrapper.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/api/python/Word2VecModelWrapper.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.mllib.api.python
 
-import java.util.{ArrayList => JArrayList, List => JList, Map => JMap}
+import java.util.{List => JList, Map => JMap}
 
 import scala.collection.JavaConverters._
 
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/classification/LogisticRegression.scala b/mllib/src/main/scala/org/apache/spark/mllib/classification/LogisticRegression.scala
index f807b5683c..c0404be019 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/classification/LogisticRegression.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/classification/LogisticRegression.scala
@@ -27,7 +27,6 @@ import org.apache.spark.mllib.optimization._
 import org.apache.spark.mllib.pmml.PMMLExportable
 import org.apache.spark.mllib.regression._
 import org.apache.spark.mllib.util.{DataValidators, Loader, Saveable}
-import org.apache.spark.mllib.util.MLUtils.appendBias
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.SQLContext
 import org.apache.spark.storage.StorageLevel
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/clustering/GaussianMixtureModel.scala b/mllib/src/main/scala/org/apache/spark/mllib/clustering/GaussianMixtureModel.scala
index 42fe27024f..02417b1124 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/clustering/GaussianMixtureModel.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/clustering/GaussianMixtureModel.scala
@@ -25,7 +25,7 @@ import org.json4s.jackson.JsonMethods._
 import org.apache.spark.SparkContext
 import org.apache.spark.annotation.Since
 import org.apache.spark.api.java.JavaRDD
-import org.apache.spark.mllib.linalg.{Matrices, Matrix, Vector}
+import org.apache.spark.mllib.linalg.{Matrix, Vector}
 import org.apache.spark.mllib.stat.distribution.MultivariateGaussian
 import org.apache.spark.mllib.util.{Loader, MLUtils, Saveable}
 import org.apache.spark.rdd.RDD
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/evaluation/MultilabelMetrics.scala b/mllib/src/main/scala/org/apache/spark/mllib/evaluation/MultilabelMetrics.scala
index 95b2fef27a..6dd541e5c0 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/evaluation/MultilabelMetrics.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/evaluation/MultilabelMetrics.scala
@@ -19,7 +19,6 @@ package org.apache.spark.mllib.evaluation
 
 import org.apache.spark.annotation.Since
 import org.apache.spark.rdd.RDD
-import org.apache.spark.SparkContext._
 import org.apache.spark.sql.DataFrame
 
 /**
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/optimization/LBFGS.scala b/mllib/src/main/scala/org/apache/spark/mllib/optimization/LBFGS.scala
index 11179a21c8..e871165161 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/optimization/LBFGS.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/optimization/LBFGS.scala
@@ -18,7 +18,6 @@
 package org.apache.spark.mllib.optimization
 
 import scala.collection.mutable
-import scala.collection.mutable.ArrayBuffer
 
 import breeze.linalg.{DenseVector => BDV}
 import breeze.optimize.{CachedDiffFunction, DiffFunction, LBFGS => BreezeLBFGS}
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/stat/correlation/SpearmanCorrelation.scala b/mllib/src/main/scala/org/apache/spark/mllib/stat/correlation/SpearmanCorrelation.scala
index 4a6c677f06..fc684d7c5f 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/stat/correlation/SpearmanCorrelation.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/stat/correlation/SpearmanCorrelation.scala
@@ -20,7 +20,6 @@ package org.apache.spark.mllib.stat.correlation
 import scala.collection.mutable.ArrayBuffer
 
 import org.apache.spark.Logging
-import org.apache.spark.SparkContext._
 import org.apache.spark.mllib.linalg.{Matrix, Vector, Vectors}
 import org.apache.spark.rdd.RDD
 
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/tree/loss/AbsoluteError.scala b/mllib/src/main/scala/org/apache/spark/mllib/tree/loss/AbsoluteError.scala
index bab7b8c6ca..48a4e38a34 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/tree/loss/AbsoluteError.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/tree/loss/AbsoluteError.scala
@@ -18,8 +18,6 @@
 package org.apache.spark.mllib.tree.loss
 
 import org.apache.spark.annotation.{DeveloperApi, Since}
-import org.apache.spark.mllib.regression.LabeledPoint
-import org.apache.spark.mllib.tree.model.TreeEnsembleModel
 
 
 /**
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/tree/loss/LogLoss.scala b/mllib/src/main/scala/org/apache/spark/mllib/tree/loss/LogLoss.scala
index b2b4594712..b88743c0db 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/tree/loss/LogLoss.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/tree/loss/LogLoss.scala
@@ -18,8 +18,6 @@
 package org.apache.spark.mllib.tree.loss
 
 import org.apache.spark.annotation.{DeveloperApi, Since}
-import org.apache.spark.mllib.regression.LabeledPoint
-import org.apache.spark.mllib.tree.model.TreeEnsembleModel
 import org.apache.spark.mllib.util.MLUtils
 
 
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/tree/loss/SquaredError.scala b/mllib/src/main/scala/org/apache/spark/mllib/tree/loss/SquaredError.scala
index 3f7d3d38be..cb97f6fd29 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/tree/loss/SquaredError.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/tree/loss/SquaredError.scala
@@ -18,8 +18,6 @@
 package org.apache.spark.mllib.tree.loss
 
 import org.apache.spark.annotation.{DeveloperApi, Since}
-import org.apache.spark.mllib.regression.LabeledPoint
-import org.apache.spark.mllib.tree.model.TreeEnsembleModel
 
 
 /**
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/tree/model/Split.scala b/mllib/src/main/scala/org/apache/spark/mllib/tree/model/Split.scala
index 783a4acb55..5cef9d0631 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/tree/model/Split.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/tree/model/Split.scala
@@ -18,7 +18,6 @@
 package org.apache.spark.mllib.tree.model
 
 import org.apache.spark.annotation.{DeveloperApi, Since}
-import org.apache.spark.mllib.tree.configuration.FeatureType
 import org.apache.spark.mllib.tree.configuration.FeatureType.FeatureType
 
 /**
diff --git a/mllib/src/test/java/org/apache/spark/ml/classification/JavaNaiveBayesSuite.java b/mllib/src/test/java/org/apache/spark/ml/classification/JavaNaiveBayesSuite.java
index f5f690eabd..07936eb79b 100644
--- a/mllib/src/test/java/org/apache/spark/ml/classification/JavaNaiveBayesSuite.java
+++ b/mllib/src/test/java/org/apache/spark/ml/classification/JavaNaiveBayesSuite.java
@@ -26,7 +26,6 @@ import org.junit.Before;
 import org.junit.Test;
 import static org.junit.Assert.assertEquals;
 
-import org.apache.spark.api.java.JavaRDD;
 import org.apache.spark.api.java.JavaSparkContext;
 import org.apache.spark.mllib.linalg.VectorUDT;
 import org.apache.spark.mllib.linalg.Vectors;
diff --git a/mllib/src/test/java/org/apache/spark/ml/clustering/JavaKMeansSuite.java b/mllib/src/test/java/org/apache/spark/ml/clustering/JavaKMeansSuite.java
index d09fa7fd56..cc5a4ef4c2 100644
--- a/mllib/src/test/java/org/apache/spark/ml/clustering/JavaKMeansSuite.java
+++ b/mllib/src/test/java/org/apache/spark/ml/clustering/JavaKMeansSuite.java
@@ -24,7 +24,6 @@ import java.util.List;
 import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
-import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
diff --git a/mllib/src/test/java/org/apache/spark/ml/feature/JavaBucketizerSuite.java b/mllib/src/test/java/org/apache/spark/ml/feature/JavaBucketizerSuite.java
index 8a1e5ef015..d707bdee99 100644
--- a/mllib/src/test/java/org/apache/spark/ml/feature/JavaBucketizerSuite.java
+++ b/mllib/src/test/java/org/apache/spark/ml/feature/JavaBucketizerSuite.java
@@ -24,7 +24,6 @@ import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
-import org.apache.spark.api.java.JavaRDD;
 import org.apache.spark.api.java.JavaSparkContext;
 import org.apache.spark.sql.DataFrame;
 import org.apache.spark.sql.Row;
diff --git a/mllib/src/test/java/org/apache/spark/ml/feature/JavaDCTSuite.java b/mllib/src/test/java/org/apache/spark/ml/feature/JavaDCTSuite.java
index 39da47381b..63e5c93798 100644
--- a/mllib/src/test/java/org/apache/spark/ml/feature/JavaDCTSuite.java
+++ b/mllib/src/test/java/org/apache/spark/ml/feature/JavaDCTSuite.java
@@ -25,7 +25,6 @@ import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
-import org.apache.spark.api.java.JavaRDD;
 import org.apache.spark.api.java.JavaSparkContext;
 import org.apache.spark.mllib.linalg.Vector;
 import org.apache.spark.mllib.linalg.VectorUDT;
diff --git a/mllib/src/test/java/org/apache/spark/ml/feature/JavaHashingTFSuite.java b/mllib/src/test/java/org/apache/spark/ml/feature/JavaHashingTFSuite.java
index d12332c2a0..5932017f8f 100644
--- a/mllib/src/test/java/org/apache/spark/ml/feature/JavaHashingTFSuite.java
+++ b/mllib/src/test/java/org/apache/spark/ml/feature/JavaHashingTFSuite.java
@@ -25,7 +25,6 @@ import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
-import org.apache.spark.api.java.JavaRDD;
 import org.apache.spark.api.java.JavaSparkContext;
 import org.apache.spark.mllib.linalg.Vector;
 import org.apache.spark.sql.DataFrame;
diff --git a/mllib/src/test/java/org/apache/spark/ml/feature/JavaPolynomialExpansionSuite.java b/mllib/src/test/java/org/apache/spark/ml/feature/JavaPolynomialExpansionSuite.java
index bf8eefd719..e22d117032 100644
--- a/mllib/src/test/java/org/apache/spark/ml/feature/JavaPolynomialExpansionSuite.java
+++ b/mllib/src/test/java/org/apache/spark/ml/feature/JavaPolynomialExpansionSuite.java
@@ -25,7 +25,6 @@ import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
-import org.apache.spark.api.java.JavaRDD;
 import org.apache.spark.api.java.JavaSparkContext;
 import org.apache.spark.mllib.linalg.Vector;
 import org.apache.spark.mllib.linalg.VectorUDT;
diff --git a/mllib/src/test/java/org/apache/spark/ml/feature/JavaStopWordsRemoverSuite.java b/mllib/src/test/java/org/apache/spark/ml/feature/JavaStopWordsRemoverSuite.java
index 848d9f8aa9..139d1d005a 100644
--- a/mllib/src/test/java/org/apache/spark/ml/feature/JavaStopWordsRemoverSuite.java
+++ b/mllib/src/test/java/org/apache/spark/ml/feature/JavaStopWordsRemoverSuite.java
@@ -24,7 +24,6 @@ import org.junit.After;
 import org.junit.Before;
 import org.junit.Test;
 
-import org.apache.spark.api.java.JavaRDD;
 import org.apache.spark.api.java.JavaSparkContext;
 import org.apache.spark.sql.DataFrame;
 import org.apache.spark.sql.Row;
diff --git a/mllib/src/test/java/org/apache/spark/ml/feature/JavaStringIndexerSuite.java b/mllib/src/test/java/org/apache/spark/ml/feature/JavaStringIndexerSuite.java
index b2df79ba74..153a08a4cd 100644
--- a/mllib/src/test/java/org/apache/spark/ml/feature/JavaStringIndexerSuite.java
+++ b/mllib/src/test/java/org/apache/spark/ml/feature/JavaStringIndexerSuite.java
@@ -25,7 +25,6 @@ import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
-import org.apache.spark.api.java.JavaRDD;
 import org.apache.spark.api.java.JavaSparkContext;
 import org.apache.spark.sql.DataFrame;
 import org.apache.spark.sql.Row;
diff --git a/mllib/src/test/java/org/apache/spark/ml/feature/JavaVectorAssemblerSuite.java b/mllib/src/test/java/org/apache/spark/ml/feature/JavaVectorAssemblerSuite.java
index e283777570..f8ba84ef77 100644
--- a/mllib/src/test/java/org/apache/spark/ml/feature/JavaVectorAssemblerSuite.java
+++ b/mllib/src/test/java/org/apache/spark/ml/feature/JavaVectorAssemblerSuite.java
@@ -24,7 +24,6 @@ import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
-import org.apache.spark.api.java.JavaRDD;
 import org.apache.spark.api.java.JavaSparkContext;
 import org.apache.spark.mllib.linalg.Vector;
 import org.apache.spark.mllib.linalg.VectorUDT;
diff --git a/mllib/src/test/java/org/apache/spark/ml/feature/JavaVectorSlicerSuite.java b/mllib/src/test/java/org/apache/spark/ml/feature/JavaVectorSlicerSuite.java
index 00174e6a68..786c11c412 100644
--- a/mllib/src/test/java/org/apache/spark/ml/feature/JavaVectorSlicerSuite.java
+++ b/mllib/src/test/java/org/apache/spark/ml/feature/JavaVectorSlicerSuite.java
@@ -25,7 +25,6 @@ import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
-import org.apache.spark.api.java.JavaRDD;
 import org.apache.spark.api.java.JavaSparkContext;
 import org.apache.spark.ml.attribute.Attribute;
 import org.apache.spark.ml.attribute.AttributeGroup;
diff --git a/mllib/src/test/java/org/apache/spark/ml/feature/JavaWord2VecSuite.java b/mllib/src/test/java/org/apache/spark/ml/feature/JavaWord2VecSuite.java
index 0c0c1c4d12..b292b1b06d 100644
--- a/mllib/src/test/java/org/apache/spark/ml/feature/JavaWord2VecSuite.java
+++ b/mllib/src/test/java/org/apache/spark/ml/feature/JavaWord2VecSuite.java
@@ -24,7 +24,6 @@ import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 
-import org.apache.spark.api.java.JavaRDD;
 import org.apache.spark.api.java.JavaSparkContext;
 import org.apache.spark.mllib.linalg.Vector;
 import org.apache.spark.sql.DataFrame;
diff --git a/mllib/src/test/scala/org/apache/spark/ml/feature/DCTSuite.scala b/mllib/src/test/scala/org/apache/spark/ml/feature/DCTSuite.scala
index 0f2aafebaf..36cafa290f 100644
--- a/mllib/src/test/scala/org/apache/spark/ml/feature/DCTSuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/ml/feature/DCTSuite.scala
@@ -25,7 +25,7 @@ import org.apache.spark.SparkFunSuite
 import org.apache.spark.ml.util.DefaultReadWriteTest
 import org.apache.spark.mllib.linalg.{Vector, Vectors}
 import org.apache.spark.mllib.util.MLlibTestSparkContext
-import org.apache.spark.sql.{DataFrame, Row}
+import org.apache.spark.sql.Row
 
 @BeanInfo
 case class DCTTestData(vec: Vector, wantedVec: Vector)
diff --git a/mllib/src/test/scala/org/apache/spark/ml/feature/StandardScalerSuite.scala b/mllib/src/test/scala/org/apache/spark/ml/feature/StandardScalerSuite.scala
index 28631cef79..8c5e47a22c 100644
--- a/mllib/src/test/scala/org/apache/spark/ml/feature/StandardScalerSuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/ml/feature/StandardScalerSuite.scala
@@ -20,7 +20,6 @@ package org.apache.spark.ml.feature
 import org.apache.spark.SparkFunSuite
 import org.apache.spark.ml.param.ParamsSuite
 import org.apache.spark.ml.util.DefaultReadWriteTest
-import org.apache.spark.mllib.feature
 import org.apache.spark.mllib.linalg.{Vector, Vectors}
 import org.apache.spark.mllib.util.MLlibTestSparkContext
 import org.apache.spark.mllib.util.TestingUtils._
diff --git a/mllib/src/test/scala/org/apache/spark/ml/feature/Word2VecSuite.scala b/mllib/src/test/scala/org/apache/spark/ml/feature/Word2VecSuite.scala
index 1671fb6f3a..80c177b8d3 100644
--- a/mllib/src/test/scala/org/apache/spark/ml/feature/Word2VecSuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/ml/feature/Word2VecSuite.scala
@@ -24,7 +24,7 @@ import org.apache.spark.mllib.feature.{Word2VecModel => OldWord2VecModel}
 import org.apache.spark.mllib.linalg.{Vector, Vectors}
 import org.apache.spark.mllib.util.MLlibTestSparkContext
 import org.apache.spark.mllib.util.TestingUtils._
-import org.apache.spark.sql.{Row, SQLContext}
+import org.apache.spark.sql.Row
 
 class Word2VecSuite extends SparkFunSuite with MLlibTestSparkContext with DefaultReadWriteTest {
 
diff --git a/mllib/src/test/scala/org/apache/spark/mllib/feature/Word2VecSuite.scala b/mllib/src/test/scala/org/apache/spark/mllib/feature/Word2VecSuite.scala
index e74ecc16ee..4fcf417d5f 100644
--- a/mllib/src/test/scala/org/apache/spark/mllib/feature/Word2VecSuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/mllib/feature/Word2VecSuite.scala
@@ -19,7 +19,6 @@ package org.apache.spark.mllib.feature
 
 import org.apache.spark.SparkFunSuite
 import org.apache.spark.mllib.util.MLlibTestSparkContext
-import org.apache.spark.mllib.util.TestingUtils._
 import org.apache.spark.util.Utils
 
 class Word2VecSuite extends SparkFunSuite with MLlibTestSparkContext {
diff --git a/mllib/src/test/scala/org/apache/spark/mllib/random/RandomRDDsSuite.scala b/mllib/src/test/scala/org/apache/spark/mllib/random/RandomRDDsSuite.scala
index 0b4c7eb302..f464d25c3f 100644
--- a/mllib/src/test/scala/org/apache/spark/mllib/random/RandomRDDsSuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/mllib/random/RandomRDDsSuite.scala
@@ -19,7 +19,6 @@ package org.apache.spark.mllib.random
 
 import scala.collection.mutable.ArrayBuffer
 
-import org.apache.spark.SparkContext._
 import org.apache.spark.SparkFunSuite
 import org.apache.spark.mllib.linalg.Vector
 import org.apache.spark.mllib.rdd.{RandomRDD, RandomRDDPartition}