Change nullable property in Dataset schema

[Kazuaki Ishizaki]

Dear all,
Would it be possible to let me know how to change nullable property in 
Dataset?

When I looked for how to change nullable property in Dataframe schema, I 
found the following approaches.
http://stackoverflow.com/questions/33193958/change-nullable-property-of-column-in-spark-dataframe
https://github.com/apache/spark/pull/13873 (Not merged yet)

However, I cannot find how to change nullable property in Dataset schema. 
Even when I wrote the following program, nullable property for "value: 
array" in ds2.schema is not changed.
If my understanding is correct, current Spark 2.0 uses an 
ExpressionEncoder that is generated based on Dataset[T] at 
https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/encoders/ExpressionEncoder.scala#L46

class Test extends QueryTest with SharedSQLContext {
  import testImplicits._
  test("test") {
    val ds1 = sparkContext.parallelize(Seq(Array(1, 1), Array(2, 2), 
Array(3, 3)), 1).toDS
    val schema = new StructType().add("array", ArrayType(IntegerType, 
false), false)
    val inputObject = BoundReference(0, 
ScalaReflection.dataTypeFor[Array[Int]], false)
    val encoder = new ExpressionEncoder[Array[Int]](schema, true,
      ScalaReflection.serializerFor[Array[Int]](inputObject).flatten,
      ScalaReflection.deserializerFor[Array[Int]],
      ClassTag[Array[Int]](classOf[Array[Int]]))
    val ds2 = ds1.map(e => e)(encoder)
    ds1.printSchema
    ds2.printSchema
  }
}

root
 |-- value: array (nullable = true)
 |    |-- element: integer (containsNull = false)

root
 |-- value: array (nullable = true)                         // Expected 
(nullable = false)
 |    |-- element: integer (containsNull = false)


Kazuaki Ishizaki