Unable to store session in Redis using Java Spring Boot Session Data Redis

I think I have problems saving session information in Redis. I've tried to follow the instruction about spring-session-data-redis, but I can't find any session information within redis when I start a request. The following is my code and config.

application.properties file:

spring.session.store-type=redis
spring.session.redis.flush-mode= on-save
spring.session.redis.namespace= spring:session
spring.redis.host= 10.10.10.10
spring.redis.port=10000

pom.xml:

<dependency>
    <groupId>org.springframework.session</groupId>
    <artifactId>spring-session-data-redis</artifactId>
</dependency>
<dependency>
    <groupId>redis.clients</groupId>
    <artifactId>jedis</artifactId>
    <version>2.9.0</version>
    <type>jar</type>
</dependency>

Application Configuration class:

@Configuration
@EnableRedisHttpSession
@PropertySource("application.properties")
public class AppConfig {

    @Value("${spring.redis.host}")
    private String redisHostName;

    @Value("${spring.redis.port}")
    private int redisPort;

    @Bean
    JedisConnectionFactory jedisConnectionFactory() {
        RedisStandaloneConfiguration redisStandaloneConfiguration = new RedisStandaloneConfiguration(
                redisHostName, redisPort);
        return new JedisConnectionFactory(redisStandaloneConfiguration);
    }
}

And my sample Get request controller:

// test only
    @CrossOrigin
    @GetMapping(value = "/test/test")
    public String justTest(HttpServletRequest request) {
        HttpSession session = request.getSession();
        session.setAttribute("sessionId", "ssssss");

        String value = (String) session.getAttribute("sessionId").toString();
        return value;
    }

Am I missing something? The spring-session-data-redis is supposed to store session to Redis automatically, but it seems not acting like that. Do I need spring-session dependency and spring-data-redis dependency? The redis connection is ok, I set it to listen to all interfaces.

It seems I can retrieve the session id when I start a request, but why the session is not inserted into Redis?