Why attribute userName not be converted，when I use @JsonIgnore on getUsername method ?

[lgl2189]

I'm using SpringSecurity
This is My UserDetail class. This class override getUsername() method from UserDetails class（from SpringSecurity）.
Because this method would cause the userName field to be ignored, resulting in only 'username' in Json. However, my field requires camel hump, so I used @JsonIgnore
But strangely, I expected to get a userName field in Json, but I didn't get anything.
So I had to add @ JsonProperty to the userName field. Fortunately, he worked and obtained userName in the json.

like this:

But my other attributes are also annotated with @ Data to obtain Getter. But they don't need @ JsonProperty.
Why can other fields be processed normally, but userName cannot？

@Data
@NoArgsConstructor
@AllArgsConstructor
public class UserDetail implements UserDetails, Serializable {

    @Serial
    private static final long serialVersionUID = 1L;

    private Integer userId;

    // 因为getUsername方法被@JsonIgnore注解，所以Json序列化时会默认不序列化userName字段
    // 使用@JsonProperty注解来指定Json序列化时属性名称，来让jackson序列化userName字段
//    @JsonProperty("userName")
    private String userName;

    private String userPassword;

    private String chinaId;

    private String realName;

    private LocalDate birthDate;

    private String phone;

    private String email;

    private List<Role> roleList;

    public UserDetail(User user, List<Role> roleList) {
        this.userId = user.getUserId();
        this.userName = user.getUserName();
        this.userPassword = user.getUserPassword();
        this.chinaId = user.getChinaId();
        this.realName = user.getRealName();
        this.birthDate = user.getBirthDate();
        this.phone = user.getPhone();
        this.email = user.getEmail();
        this.roleList = roleList;
    }

    @JsonIgnore
    @Override
    public Collection<? extends GrantedAuthority> getAuthorities() {
        if (roleList == null || roleList.isEmpty()) {
            return Collections.emptyList();
        }
        return roleList.stream()
                .map(role -> new SimpleGrantedAuthority("ROLE_" + role.getRoleTag()))
                .collect(Collectors.toList());
    }

    @JsonIgnore
    @Override
    public String getPassword() {
        return userPassword;
    }

    // 在Json序列化时，忽略掉这个方法，避免影响到userName，导致前端代码期望的属性名称为userName，而JSON序列化时属性名称为username
    @JsonIgnore
    @Override
    public String getUsername() {
        return userName;
    }

    @JsonIgnore
    @Override
    public boolean isAccountNonExpired() {
        return true;
    }

    @JsonIgnore
    @Override
    public boolean isAccountNonLocked() {
        return true;
    }

    @JsonIgnore
    @Override
    public boolean isCredentialsNonExpired() {
        return true;
    }

    @JsonIgnore
    @Override
    public boolean isEnabled() {
        return true;
    }
}

@Component
public class UserLoginSuccessHandler implements AuthenticationSuccessHandler {

    private final ObjectMapper objectMapper;
    private final RedisTemplate<String,Object> redisTemplate;

    @Autowired
    public UserLoginSuccessHandler(ObjectMapper objectMapper, RedisTemplate<String,Object> redisTemplate) {
        Assert.notNull(objectMapper, "ObjectMapper must not be null");
        Assert.notNull(redisTemplate, "RedisTemplate must not be null");
        this.objectMapper = objectMapper;
        this.redisTemplate = redisTemplate;
    }

    @Override
    public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response, FilterChain chain, Authentication authentication) throws IOException, ServletException {
        onAuthenticationSuccess(request, response, authentication);
    }

    @Override
    public void onAuthenticationSuccess(HttpServletRequest request, HttpServletResponse response, Authentication authentication) throws IOException, ServletException {
        //生成JWT
        //TODO: 将JWT生成逻辑抽象到工具类中
        UserDetail userDetail = UserUtil.removeSensitiveInfo(
                (UserDetail) authentication.getPrincipal());
        String userJson = objectMapper.writeValueAsString(userDetail);
        String jwt = JWTUtil.createToken(Map.of("user", userJson), Constant.JWT_SECRET_BYTE);
        //存入redis
        redisTemplate.opsForHash().put(Constant.REDIS_TOKEN_KEY,userDetail.getUserId().toString(),jwt);
        Result result = ResultUtil.success_200(Map.of("token", jwt), "登陆成功");
        String json = objectMapper.writeValueAsString(result);
        response.setContentType("application/json");
        response.getWriter().write(json);
    }
}