OpenApiSpex.Plug.RenderSpec.init/1 is undefined

Trying to use open_api_spex in my phoenix project.

When I try compiling the project with mix a warning pops us
OpenApiTest.OpenApiSpex.Plug.RenderSpec.init/1 is undefined

I have my router defined as below:

defmodule OpenApiTestWeb.Router do
  use OpenApiTestWeb, :router

  pipeline :browser do
    plug :accepts, ["html"]
    plug :fetch_session
    plug :fetch_flash
    plug :protect_from_forgery
    plug :put_secure_browser_headers
  end

  pipeline :api do
    plug :accepts, ["json"]
    plug OpenApiSpex.Plug.PutApiSpec, module: OpenApiTestWeb.ApiSpec
  end

  scope "/", OpenApiTestWeb do
    pipe_through :browser

    get "/", PageController, :index
    get "/payments", PaymentController, :create_payment
    get "/openapi", OpenApiSpex.Plug.RenderSpec, []
  end

  if Mix.env() in [:dev, :test] do
    import Phoenix.LiveDashboard.Router

    scope "/" do
      pipe_through :browser
      live_dashboard "/dashboard", metrics: OpenApiTestWeb.Telemetry
    end
  end
end

OpenApiSpex.Plug.RenderSpec module is present in the deps as below.

defmodule OpenApiSpex.Plug.RenderSpec do


      defmodule MyAppWeb.Router do
        use Phoenix.Router
        alias MyAppWeb.UserController

        pipeline :api do
          plug :accepts, ["json"]
          plug OpenApiSpex.Plug.PutApiSpec, module: MyAppWeb.ApiSpec
        end

        scope "/api" do
          pipe_through :api
          resources "/users", UserController, only: [:create, :index, :show]
          get "/openapi", OpenApiSpex.Plug.RenderSpec, []
        end
      end


  alias OpenApiSpex.Plug.PutApiSpec
  @behaviour Plug
  @json_encoder Enum.find([Jason, Poison], &Code.ensure_loaded?/1)

  @impl Plug
  def init(opts), do: opts

  @impl Plug
  def call(conn, _opts) do
    {spec, _} = PutApiSpec.get_spec_and_operation_lookup(conn)

    conn
    |> Plug.Conn.put_resp_content_type("application/json")
    |> Plug.Conn.send_resp(200, @json_encoder.encode!(spec))
  end
end

Could someone kindly help?