spark wrong encoder for non product class

sparkEncoder.scala

import org.apache.spark.SparkConf
import org.apache.spark.sql.{ Encoder, Encoders, SparkSession }

class SomeOtherClass(foo: Int)
case class FooWithSomeOtherClass(a: Int, b: String, bar: SomeOtherClass)
case class FooWithoutOtherClass(a: Int, b: String, bar: Int)
case class Foo(a: Int)

object EncoderSpark extends App {

  var conf: SparkConf = new SparkConf()
    .setMaster("local[*]")
    .setAppName("endoeerTesting")
  val spark = SparkSession
    .builder()
    .config(conf)
    .getOrCreate()

  import spark.implicits._

  implicit val someOtherClassEncoder: Encoder[SomeOtherClass] = Encoders.kryo[SomeOtherClass]

  val df1 = Seq(Foo(1), Foo(2)).toDF

  val df2 = Seq(FooWithSomeOtherClass(1, "one", new SomeOtherClass(4))).toDS

  val df3 = Seq(FooWithoutOtherClass(1, "one", 1), FooWithoutOtherClass(2, "two", 2)).toDS
  df3.printSchema
  df3.show

  val df4 = df3.map(d => FooWithSomeOtherClass(d.a, d.b, new SomeOtherClass(d.bar)))
  df4.printSchema
  df4.show
  df4.collect

  spark.stop

}