如何将额外的数据帧传递给自定义Spark MLLib转换器

import org.apache.spark.ml.Transformer
import org.apache.spark.ml.param.Param
import org.apache.spark.ml.param.ParamMap
import org.apache.spark.ml.util.Identifiable
import org.apache.spark.sql.DataFrame
import org.apache.spark.sql.functions._

class CustomTransformer(override val uid: String) extends Transformer {
  def this() = this(Identifiable.randomUID("customTransformer"))

  val extraDataFrame: Param[DataFrame] = new Param(this, "extraDataFrame", "extra data frame")

  def setExtraDataFrame(value: DataFrame): this.type = set(extraDataFrame, value)

  def getExtraDataFrame: DataFrame = $(extraDataFrame)

  override def transform(dataset: DataFrame): DataFrame = {
    val extraData = getExtraDataFrame
    // 进行转换操作，例如将额外数据帧与输入数据帧进行合并
    val transformedData = dataset.join(extraData, Seq("id"), "left_outer")
    transformedData
  }

  override def copy(extra: ParamMap): CustomTransformer = {
    val copied = new CustomTransformer(uid)
    copyValues(copied, extra)
    copied.setExtraDataFrame(getExtraDataFrame)
  }
}

// 使用示例
val inputDF: DataFrame = ...
val extraDF: DataFrame = ...

val customTransformer = new CustomTransformer()
  .setExtraDataFrame(extraDF)

val transformedDF = customTransformer.transform(inputDF)