如何在spring boot中不返回为空的对象值

import com.fasterxml.jackson.annotation.JsonInclude;

@JsonInclude(JsonInclude.Include.NON_NULL)
public class User {
    private String name;
    private Integer age;

    // getters and setters
}

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class JacksonConfig {

    @Bean
    public ObjectMapper objectMapper() {
        ObjectMapper mapper = new ObjectMapper();
        mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
        return mapper;
    }
}

import java.util.Optional;

@RestController
public class UserController {

    @GetMapping("/user/{id}")
    public Optional<User> getUserById(@PathVariable Long id) {
        // 模拟从数据库获取用户
        User user = findUserById(id);
        return Optional.ofNullable(user);
    }

    private User findUserById(Long id) {
        // 模拟数据库查询
        return null;
    }
}

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
public @interface ExcludeNullValues {
}

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.springframework.stereotype.Component;

@Aspect
@Component
public class ExcludeNullValuesAspect {

    @Around("@annotation(ExcludeNullValues)")
    public Object around(ProceedingJoinPoint joinPoint) throws Throwable {
        Object result = joinPoint.proceed();
        if (result instanceof Iterable) {
            // 处理集合类型的空值
        } else if (result != null) {
            // 处理单个对象的空值
        }
        return result;
    }
}