I’m learning Spring Boot with Spring Security, and I’m having trouble with a @PostMapping endpoint in my AuthController. The @GetMapping endpoint works fine, but the @PostMapping endpoint is never hit. I’ve verified the request using Postman, and everything seems correct. Here are the details:

Security Configuration (SecurityConfig):

@Configuration
@EnableWebSecurity
@EnableMethodSecurity
public class SecurityConfig {
    @Bean
    public UserDetailsService userDetailsService() {
        // Define your custom UserDetailsService implementation
        return new CustomUserDetailsService();
    }

    @Bean
    public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
        http
                .authorizeHttpRequests(req ->
                        req.requestMatchers(
                                        "/auth/**",
                                        "/css/**.css",
                                        "/js/**"
                                ).permitAll()
                                .anyRequest().authenticated()
                )
                .sessionManagement(session -> session.sessionCreationPolicy(SessionCreationPolicy.STATELESS));

        return http.build();
    }

    @Bean
    public AuthenticationManager authenticationManager(AuthenticationConfiguration authenticationConfiguration) throws Exception {
        return authenticationConfiguration.getAuthenticationManager();
    }
}

AuthController:

@RestController
@RequestMapping("/auth")
public class AuthController {
    @GetMapping("/test")
    public String test() {
        return "Testing GET in Auth Ctrl.";
    }

    @PostMapping("/login")
    public String login(@RequestBody AuthRequest authRequest) {
        try {
            if(authRequest.getUsername() == null || authRequest.getPassword() == null)
                throw new AuthenticationException("AuthRequest is empty");

            // Assuming successful authentication, you would normally return a JWT token here
            return "Login successful!";
        } catch (AuthenticationException e) {
            return "Login failed!";
        }
    }
}

@Data
@NoArgsConstructor
class AuthRequest {
    private String username;
    private String password;
}

CustomUserDetailsService :

@Service
public class CustomUserDetailsService implements UserDetailsService {
    private final Map<String, String> usersMap = new HashMap<>();

    @Autowired
    public CustomUserDetailsService() {
        // Initialize the usersMap with encoded passwords
        usersMap.put("ricky", "$2a$10$Dow1SE9N1XzFxXh3YDJIoO/b0Zi4DlCg8Up7X5DpIS9b/T/xkaHOO"); // password: 123
        usersMap.put("martin", "$2a$10$Dow1SE9N1XzFxXh3YDJIoO/b0Zi4DlCg8Up7X5DpIS9b/T/xkaHOO"); // password: 456
    }

    @Override
    public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        if (usersMap.containsKey(username)) {
            return new User(username, usersMap.get(username), new ArrayList<>()); // Empty authorities list
        }

        // If this is thrown, then we won't generate a JWT token.
        throw new UsernameNotFoundException(username + " not found.");
    }
}

Testing with Postman:

URL: http://localhost:8080/auth/login
Method: POST
Headers: Content-Type: application/json
Body: Raw JSON
Example body:

{
    "username": "ricky",
    "password": "123"
}

What I’ve Tried:

1. Verified that the @GetMapping endpoint works.
2. Ensured that the POST request is correctly formatted and sent with the appropriate headers.
3. Checked that the /auth/login endpoint is permitted in the security configuration.
4. Added request logging to see if the request is being received by Spring.
5. Simplified the controller to rule out other potential issues.

Problem:
Despite the above steps, the @PostMapping endpoint is never hit, and no error messages are logged. The @GetMapping endpoint works fine.

Additional Information:
pom.xml

Any insights or suggestions on why the @PostMapping endpoint is not being hit would be greatly appreciated!