[SPARK-23870][ML] Forward RFormula handleInvalid Param to VectorAssembler to handle invalid values in non-string columns

## What changes were proposed in this pull request?

`handleInvalid` Param was forwarded to the VectorAssembler used by RFormula.

## How was this patch tested?

added a test and ran all tests for RFormula and VectorAssembler

Author: Yogesh Garg <yogesh(dot)garg()databricks(dot)com>

Closes apache#20970 from yogeshg/spark_23562.

Author: Yogesh Garg

mllib/src/main/scala/org/apache/spark/ml/feature/RFormula.scala

@@ -278,6 +278,7 @@ class RFormula @Since("1.5.0") (@Since("1.5.0") override val uid: String)
     encoderStages += new VectorAssembler(uid)
       .setInputCols(encodedTerms.toArray)
       .setOutputCol($(featuresCol))
+      .setHandleInvalid($(handleInvalid))
     encoderStages += new VectorAttributeRewriter($(featuresCol), prefixesToRewrite.toMap)
     encoderStages += new ColumnPruner(tempColumns.toSet)
 

mllib/src/test/scala/org/apache/spark/ml/feature/RFormulaSuite.scala

@@ -17,6 +17,7 @@
 
 package org.apache.spark.ml.feature
 
+import org.apache.spark.SparkException
 import org.apache.spark.ml.attribute._
 import org.apache.spark.ml.linalg.{Vector, Vectors}
 import org.apache.spark.ml.param.ParamsSuite
@@ -592,4 +593,26 @@ class RFormulaSuite extends MLTest with DefaultReadWriteTest {
         assert(features.toArray === a +: b.toArray)
     }
   }
+
+  test("SPARK-23562 RFormula handleInvalid should handle invalid values in non-string columns.") {
+    val d1 = Seq(
+      (1001L, "a"),
+      (1002L, "b")).toDF("id1", "c1")
+    val d2 = Seq[(java.lang.Long, String)](
+      (20001L, "x"),
+      (20002L, "y"),
+      (null, null)).toDF("id2", "c2")
+    val dataset = d1.crossJoin(d2)
+
+    def get_output(mode: String): DataFrame = {
+      val formula = new RFormula().setFormula("c1 ~ id2").setHandleInvalid(mode)
+      formula.fit(dataset).transform(dataset).select("features", "label")
+    }
+
+    assert(intercept[SparkException](get_output("error").collect())
+      .getMessage.contains("Encountered null while assembling a row"))
+    assert(get_output("skip").count() == 4)
+    assert(get_output("keep").count() == 6)
+  }
+
 }