Mage2\Checkout\Controllers\CheckoutController::postShippingAddress PHP Method

    public function postShippingAddress(AddressRequest $request)
    {
        $orderData = Session::get('order_data');
        $user = Auth::user();
        $request->merge(['user_id' => $user->id]);
        $request->merge(['type' => 'SHIPPING']);
        if ($request->get('id') > 0) {
            $address = Address::findorfail($request->get('id'));
            $address->update($request->all());
        } else {
            $address = Address::create($request->all());
        }
        $orderData['shipping_address_id'] = $orderData['shipping_address_id'] = $address->id;
        Session::put('order_data', $orderData);
        return redirect()->route('checkout.step.billing-address');
    }