How to declare :map in Absinthe.Schema.Notation.object/3

I’m trying to impelent GraphQL API in my project. I’m new in GraphQL, only read one article. I don’t understand how to convert :map field from Ecto.Schema to Types for GraphQL Schema. How i can declare field :locales in Absinthe.Schema.Notation.object/3?

My Ecto.Schema is

defmodule Msg
  @primary_key {:id, MsgidType, autogenerate: false}
  typed_schema "messages" do
    field(:text, :string)
    field(:domain, :string)
    field(:locales, :map, default: %{})

    timestamps()
  end
end

Example of %Msg{}

 %Msg{
    id: "test_update_msg_id",
    text: "Update test",
    domain: "test",
    locales: %{
      "en" => "Check update",
      "ru" => "Proverka update",
      "uz" => "Imtihon update"
    }
  }

My Absinthe.Schema.Notation

  @desc "Message for sms and ussd"
  object :message do
    field(:id, non_null(:string), description: "Hardcoded id")
    field(:text, non_null(:string), description: "Default text")
    field(:domain, :string)
    field(:locales, ???)
  end