@ConfigurationProperties 的作用是什么

@Component
@PropertySource("classpath:my.properties")
@ConfigurationProperties(prefix = "user")
public class MyConfig {
 
	private String username;
	private int age;
 
	public String getUsername() {
		return username;
	}
 
	public void setUsername(String username) {
		this.username = username;
	}
 
	public int getAge() {
		return age;
	}
 
	public void setAge(int age) {
		this.age = age;
	}
 
	@Override
	public String toString() {
		return "username=" + username + ",age=" + age;
	}
}

my.properties 
user.username=zhangsan user.age=20

@RestController
@RequestMapping("/api")
public class Index {
	
	@Autowired
	MyConfig myconfig;
	
 
    @GetMapping("/index")
    public Object getStateStatistics() {
        Map<String,String> m=new HashMap<>();
        m.put("status", myconfig.toString());
        return m;
    }
}