:not is not checked

[lud-wj]

Reproductible example:

defmodule MySchema do
  alias OpenApiSpex.Schema
  require OpenApiSpex

  OpenApiSpex.schema(%{
    title: "Object",
    type: :object,
    not: %Schema{type: :object, properties: %{code: %Schema{enum: ["bad_code", type: :string]}}},
    properties: %{code: %Schema{type: :string}}
  })
end

defmodule MySpec do
  alias OpenApiSpex.Components
  alias OpenApiSpex.Info
  alias OpenApiSpex.OpenApi

  def spec do
    %OpenApi{
      servers: [],
      info: %Info{
        title: to_string(Application.spec(:my_app, :description)),
        version: to_string(Application.spec(:my_app, :vsn))
      },
      paths: %{},
      components: %Components{
        schemas: %{"MySchema" => MySchema.schema()}
      }
    }
    |> OpenApiSpex.resolve_schema_modules()
  end
end

OpenApiSpex.TestAssertions.assert_schema(%{"code" => "good_code"}, "MySchema", MySpec.spec()) |> dbg()
OpenApiSpex.TestAssertions.assert_schema(%{"code" => "bad_code"}, "MySchema", MySpec.spec()) |> dbg()

Bot calls at the bottom return the valid data, while the second one should raise because "bad_code" is forbidden.

EDIT: Well, looking at the 3.0 specification, it seems that not is not a supported keyword. What is it supposed to do in OpenApiSpex?