Using @ModelAttribute and RedirectAttributes

I have a controller with the following methods:

    @RequestMapping(value = "/register", method = RequestMethod.GET)
    public String register(Model model) {
        model.addAttribute("user", new User());
        return "register";
    }

    @RequestMapping(value = "/registration", method = RequestMethod.POST)
    public String registration(@ModelAttribute("user") User user, BindingResult bindingResult, RedirectAttributes redirectAttributes) {
        UserValidator validator = new UserValidator();
        validator.validate(user, bindingResult);

        if (bindingResult.hasErrors()) {
            redirectAttributes.addFlashAttribute(BindingResult.MODEL_KEY_PREFIX + "user", bindingResult);
            redirectAttributes.addFlashAttribute("user", user);

            return "redirect:/register";
        }
        ...
    }

My jsp:

<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>

<form:form method="POST" modelAttribute="user" action="/registration">
    <div>
        <label>First Name</label>
        <form:input path="firstName"/>
        <form:errors path="firstName"/>
    </div>
    <div>
        <label>Last Name</label>
        <form:input path="lastName"/>
        <form:errors path="lastName"/>
    </div>
    <div>
        <label>E-mail</label>
        <form:input path="email"/>
        <form:errors path="email"/>
    </div>
    <div>
        <label>Password</label>
        <form:password path="password"/>
        <form:errors path="password"/>
    </div>

    <input type="submit" value="Submit"/>
</form:form>

However, if there are errors they are not shown after the redirect because I create a new user every time the /register is called. Is there a way to fix this without storing the user in a session?

I can create another method just for this case so I can redirect to /register2 without losing the user:

@RequestMapping(value = "/register2", method = RequestMethod.GET)
public String register2() {
    return "register";
}

It worked like I wanted, but it's a very bad approach.