defmodule Common do
  @callback request(term) :: term

  defmacro __using__(_) do
    quote do
      @behaviour Common

      def get_stat(from, to, opts), do: Common.get_stat(__MODULE__, from, to, opts)

      @impl Common
      def request(opts), do: opts

      defoverridable request: 1
    end
  end

  def get_stat(module, from, to, opts), do: module.request(%{from: from, to: to} |> Map.merge(opts))
end

defmodule A do
  use Common

  def request(opts), do: super(opts) |> Map.put_new(:keys, Map.keys(opts))
end

defmodule B do
  use Common
end

iex(1)> B.get_stat(1, 2, %{})
%{from: 1, to: 2}
iex(2)> A.get_stat(1, 2, %{})
%{from: 1, keys: [:from, :to], to: 2}
iex(3)> A.get_stat(1, 2, %{opt: :val})
%{from: 1, keys: [:from, :opt, :to], opt: :val, to: 2}
iex(4)> A.get_stat(1, 2, %{keys: [:val1, :val2]})
%{from: 1, keys: [:val1, :val2], to: 2}