fix errors

Author: yinxusen

mllib/src/main/scala/org/apache/spark/ml/tuning/CrossValidator.scala

@@ -32,6 +32,7 @@ import org.apache.spark.ml.feature.RFormulaModel
 import org.apache.spark.ml.param._
 import org.apache.spark.ml.param.shared.HasSeed
 import org.apache.spark.ml.util._
+import org.apache.spark.ml.util.DefaultParamsReader.Metadata
 import org.apache.spark.mllib.util.MLUtils
 import org.apache.spark.sql.DataFrame
 import org.apache.spark.sql.types.StructType

mllib/src/main/scala/org/apache/spark/ml/tuning/TrainValidationSplit.scala

@@ -20,7 +20,6 @@ package org.apache.spark.ml.tuning
 import org.apache.hadoop.fs.Path
 import org.json4s.DefaultFormats
 
-import org.apache.spark.Logging
 import org.apache.spark.annotation.{Experimental, Since}
 import org.apache.spark.internal.Logging
 import org.apache.spark.ml.{Estimator, Model}