# Alternative approach using ISOMsg.clone/1 + filtering
defp clone_supported_fields_alternative(%ISOMsg{} = message) do
  supported_fields = [2, 3, 4, 11, 12, 13, 14, 22, 23, 24, 25, 35, 37, 38, 39, 41, 42, 49, 52, 55, 62, 63]
  
  # Step 1: Clone the entire message (preserves ISOComponent structure)
  cloned_message = ISOMsg.clone(message)
  
  # Step 2: Remove unsupported fields
  filtered_message = 
    cloned_message.fields
    |> Map.keys()
    |> Enum.reduce(cloned_message, fn field_num, acc_msg ->
      if field_num in supported_fields do
        acc_msg  # Keep supported fields
      else
        ISOMsg.unset(acc_msg, field_num)  # Remove unsupported fields
      end
    end)
  
  {:ok, filtered_message}
end