Example of excluding a field in Genson that is not working

GensonSpec.scala

import com.owlike.genson._
import com.owlike.genson.reflect.VisibilityFilter
import org.scalatest.WordSpecLike

case class TestEntity(name: String, date: Long, amount: Int)

class GensonSpec extends WordSpecLike {

  val genson = new GensonBuilder()
    .withBundle(ScalaBundle())
    .useFields(true, VisibilityFilter.PRIVATE)
    .useIndentation(true)
    .exclude("amount")
    .create()

  "Genson" must {
    "Test" in {
      val jsonOut = genson.toJson( TestEntity("Hi",100L,10) )
      println( jsonOut )
    }
  }
}

STDOUT:

{
"amount":10,
"date":100,
"name":"Hi"
}