Как после обновление страницы обновлять значение рандома в коде?

public class Captcha {
    
        private final List<String> list = new ArrayList<>(Arrays.asList("qwert1","ahb28fsa","p3fe@","p09kfQ"));
    
    
        public String getList() {
                int a = (int) (Math.random() * 3);
            return list.get(a);
        }
    }

Контролер

@GetMapping("/buy")
    public String buyPage(Model model) {
        model.addAttribute("cap", neBot);
        return "buy-page";
    }



    @PostMapping("/buy")
    public String emailInfo(@RequestParam String mail, @RequestParam String name, @RequestParam String phone, @RequestParam String text,@RequestParam String captcha,Model model){
       if (captcha.equals(neBot)){
            Email email = new Email(mail, name, phone, text);
            emailRepository.save(email);
        }
        return "redirect:/";
    }
    

форма html

  <form action="/buy" method="post">
            <img class="mb-4" src="https://static.vecteezy.com/ti/vecteur-libre/p1/2775409-pharmacie-pharmacie-vector-logo-vectoriel.jpg" alt="" width="150" height="140">
            <h1 class="h3 mb-3 fw-normal">Please sign in</h1>
    
            <div class="form-floating m-auto">
                <input type="email" class="form-control" id="floatingInput" placeholder="[email protected]" name="mail">
                <label for="floatingInput">Email address</label>
            </div>
            <br>
            <div class="form-floating">
                <input class="form-control" id="floatingPhone" placeholder="phone" type="text" name="phone">
                <label for="floatingPhone">Phone</label>
            </div>
            <br>
            <div class="form-floating">
                <input class="form-control" id="floatingName" placeholder="your name" type="text" name="name">
                <label for="floatingName">name</label>
            </div>
            <br>
            <div class="form-floating">
                <textarea class="form-control" id="ms" placeholder="Your order" type="text" name="text"></textarea>
                <label for="ms">Your order</label>
            </div>
            <br>
            <div class="form-floating">
                <div>
                    <p th:text="'Каптча ' + ${cap}"></p>
    
                </div>
            </div>
            <br>
            <div class="form-floating">
                <input class="form-control" id="floatingCaptcha" placeholder="phone" type="text" name="captcha">
                <label for="floatingCaptcha">Captcha</label>
            </div>
            <br>
            <button class="w-100 btn btn-lg btn-primary" type="submit">Send</button>

Есть такой код самодельной капчи как сделать что бы обновлялась значение капчи после обновление стр если такое можно сделать?