'sometimes|nullable|string', 'billing_postal_code' => 'required|string', 'billing_vat_number' => 'required|string', 'billing_address' => 'required|string', 'billing_country' => 'required|string', 'billing_state' => 'required|string', 'billing_city' => 'required|string', 'billing_name' => 'required|string', ]; } }