Good morning. I have the following problem. I should read the contents of the following Dynamo table through the ExAws library:

{
  "actorengine": "HOT-TCM",
  "actortype": "BUSINESS_ACTOR",
  "actorversionclass": 1,
  "classified": "UNCLASSIFIED",
  "creatorclass": "ivan.casiraghi@gmail.com",
  "datadeploy": "2019-02-11 16:55:13",
  "encryption": "NOENCRYPTION",
  "id": "1234567890",
  "inclassparameters": [
    {
      "id": "1222",
      "keyspace": "eyspace"
    }
  ],
  "keyspace": "it0125maxwellgroup",
  "linknamemodel": "https://s3-eu-west.amazonaws.com/maxwell-abe-deploy/actor/it0125maxwellgroup/prova01_1.0.json",
  "name": "prova01",
  "security": "PUBLIC",
  "statedeploy": "ACTIVE"
}

This is my module:

defmodule ElixirCrudWeb.Resolver.Resolver do
  @moduledoc false


  alias ExAws.Dynamo


  defmodule InClassParameter do
    @derive [ExAws.Dynamo.Encodable]
    defstruct [:keyspace, :id]
  end



  defmodule ActorClassBusiness do
        @derive [ExAws.Dynamo.Encodable]
        defstruct [:id, :actorversionclass, :actorengine, :actortype, :classified, :creatorclass, :datadeploy,
          :encryption, :keyspace, :linknamemodel, :name,  :security, :statedeploy,
          inClassParameter: [%InClassParameter{},]
        ]
      end
 def select_one(_parent, %{id: id}, _resolution)  do
    item = Dynamo.get_item("actorClassBusiness", %{id: id}) |> ExAws.request!
    wrap_result(id, item)
  end


  defp wrap_result(key, map) when map == %{} do
    {:error, "actorClassBusiness ID #{key} not found"}
  end

  defp wrap_result(_, map) do
    IO.puts("Ecco i dati  #{inspect(map)}")
    item = Dynamo.decode_item(map, as: ActorClassBusiness)
    {:ok, item}
  end

end

If I run the query from GraphiQl:

query read{
  selectOne(id: "14c41f17-38b8-41db-af8b-111f6165932a"){
    id
    actorengine
  actortype
  actorversionclass
  classified
  creatorclass
  datadeploy
  encryption
    statedeploy
    inclassparameters{
      id
      keyspace
    }
  }
}

I get the following:

{
  "data": {
    "selectOne": {
      "actorengine": "HOT-TCM",
      "actortype": "BUSINESS_ACTOR",
      "actorversionclass": 1,
      "classified": "UNCLASSIFIED",
      "creatorclass": "ascanio.casiraghi@gmail.com",
      "datadeploy": "2019-03-18 01:48:59",
      "encryption": "NOENCRYPTION",
      "id": "14c41f17-38b8-41db-af8b-111f6165932a",
      "inclassparameters": null,
      "statedeploy": "ACTIVE"
    }
  }
}

inclassparameter is NULL. Where am I wrong?
Thank you