Spring Boot Application: NullPointerException using @ModelAttribute

Question

I'm getting a NullPointerException in these @ModelAttribute variables.

Here is my code:

@RequestMapping(value="/newUser", method=RequestMethod.POST)
public String newUser(@Validated @ModelAttribute("user") User user, BindingResult userBindingResult, @Validated @ModelAttribute("credentials") Credentials credentials, BindingResult credentialsBindingResult, @Validated @ModelAttribute("contacts") Contacts contacts, BindingResult contactsBindingResult, @Validated @ModelAttribute("address") Address address, BindingResult addressBindingRusult, Model model) {
    
    this.userValidator.validate(user, userBindingResult);
    this.credentialsValidator.validate(credentials, credentialsBindingResult);
    this.contactsValidator.validate(contacts, contactsBindingResult);
    this.addressValidator.validate(address, addressBindingRusult);
    
    if (!userBindingResult.hasErrors() && !credentialsBindingResult.hasErrors() && !contactsBindingResult.hasErrors() && !addressBindingRusult.hasErrors()) {
        
        user.setContacts(contacts);
        user.setAddress(address);
        credentials.setUser(user);
        credentials.setRole(Credentials.DEFAULT_ROLE);
        credentials.setPassword(passwordEncoder.encode(credentials.getPassword()));
        credentials.setEnabled(true); 
        credentialsService.saveCredentials(credentials);
        
        return "redirect:/dashboard?successUser";
        
    } else {
        return "redirect:/dashboard?errorUser";
    }
}

I added to the model these attributes in a previous GET method when the page loads and I checked in Chrome console that data are sent through by the form. Here is part of my code for the GET method:

@RequestMapping(value= {"/dashboard"}, method= RequestMethod.GET)
public String loadDashboardPage (Model model) {
    
    /*Users signup*/
    model.addAttribute("user", new User());
    model.addAttribute("credentials", new Credentials());
    model.addAttribute("contacts", new Contacts());
    model.addAttribute("address", new Address());

    return "dashboard";
}

Here is the error I got in my Eclipse console:

java.lang.NullPointerException: null
at com.applicationSample.App.validator.userValidator.validate(UserValidator.java:46) ~[classes/:na]
at com.applicationSample.App.controller.SignupController.newUser(SignupController.java:144) ~[classes/:na]

Here you can find the code for the Validator class:

@Override
public void validate(Object target, Errors errors) {
    
    User user = (User) target;
    String name = user.getName().trim();
    String surname = user.getSurname().trim();
    
    if (name.isEmpty()) {
        errors.rejectValue("name", "required");
    }

    if (surname.isEmpty()) {
        errors.rejectValue("surname", "required"); 
    }
}

I'm using Thymeleaf in my html files to bind data. Also I've already used that approach in a similar method and it's working fine. I can't see where the error could be, any help?