import com.microsoft.ml.spark.LightGBMClassificationModel
import org.apache.spark.ml.classification.RandomForestClassificationModel

def getFeatureImportances(inputContainer: PipelineModelContainer): (String, String) = {

    val transformer = inputContainer.pipelineModel.stages.last

    val featureImportancesVector = inputContainer.params match {

        case RandomForestParameters(numTrees, treeDepth, featureTransformer) => transformer.asInstanceOf[RandomForestClassificationModel].featureImportances
        case LightGBMParameters(treeDepth, numLeaves, iterations, featureTransformer) => transformer.asInstanceOf[LightGBMClassificationModel].getFeatureImportances("split")
}

    val colNames = inputContainer.featureColNames
    val sortedFeatures = (colNames zip featureImportancesVector.toArray).sortWith(_._2 > _._2).zipWithIndex

value toArray is not a member of java.io.Serializable