Why session value is printing the whole session?

Gatling (Open-Source)
1

Hi Team,

exec {
  session =>
    val fulfill = session.get("fulfillOrderId").as[String]
    val abc = fulfill + "_containerList"
    println("*******************" + session.get(s"${fulfill}_containerList".toString).as[Seq[String]])
    session.set("key",session.get(s"${fulfill}_containerList".toString).as[Seq[String]])
    println("key:"+session("key"))

I am executing the above code.

first println statement is printing as expected output “*******************Vector(D10442)”

When I try to assign the same session sequence to another session called “key” parameter, it is printing the whole session description.

What is wrong here?