Do i correctly use PRG pattern in Java servlet or should i do someting else?

I have this controller and in Get method I use request dispatcher and in Post I use redirect.

@WebServlet(name = "ControllerOrder", value = "/User/Order")
public class ControllerOrder extends HttpServlet {
    private static final Logger LOGGER = Logger.getLogger(ControllerOrder.class);
    private MySQLCarCategoryDao categoryDao;
    @Override
    public void init() throws ServletException {
        super.init();
        MySQLDAOFactory dao = (MySQLDAOFactory) getServletContext().getAttribute("MySQLFactory");
         categoryDao = (MySQLCarCategoryDao) dao.getCarCategoryDao();
    }
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ImageManager manager = ImageManager.getInstance();
        List<CarCategory> carCategories = categoryDao.findExistingCarC();
        List<ToggleButton> buttons = IntStream.range(0, carCategories.size())
                .mapToObj(i -> {
                    ToggleButton button = new ToggleButton();
                    button.setIcon("img:data:image/png;base64," + manager.getBase64String(manager.imageToByte(carCategories.get(i).getCarCategoryImage())));
                    button.setValue(carCategories.get(i).getCarCategory());
                    button.setSlot(i+1+"");
                    return button;
                })
                .collect(Collectors.toList());
        ObjectMapper mapper = new ObjectMapper();
        try {
            request.setAttribute("CarCategories",carCategories);
            request.setAttribute("CarCategoriesButtons",mapper.writeValueAsString(buttons));
        } catch (JsonProcessingException e) {
            LOGGER.error(e);
        }
        request.getRequestDispatcher("/WEB-INF/view/order.jsp").forward(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        HttpSession session = request.getSession();
        String login = (String) session.getAttribute("Login");
        String userAddress = request.getParameter("userAddress");
        String userDestination = request.getParameter("userDestination");
        String[] stingNumbers = request.getParameterValues("numOfPas");
        String[] categories = request.getParameterValues("categories");
        if(stingNumbers != null && stingNumbers.length > 0&&categories != null && categories.length > 0) {
            OrdersMaker maker = new OrdersMaker();
           String message = maker.makeOrder(stingNumbers,categories,userAddress,userDestination,login);
            if(message.startsWith("false")){
                response.sendRedirect(request.getContextPath() + "/User/Order?NotAvailable=" + message);
                return;
            }
            response.sendRedirect(request.getContextPath() + "/User/Order?takenTime=" + message);
        }
    }
}

I know you could say this pattern is easily understand but I want to know that I'm doing all right. Thanks for answering.