TestSpringBootConf.java

public class Person {
    public Person() {
        System.out.println("I was created");
    }

    @PostConstruct
    private void init() {
        System.out.println("I was constructed");
    }
}

@Configuration
public class Conf {
    @Bean
    public Person person() {
        return new Person();
    }

    @Bean
    public Book book() {
        var oldPerson = person();
        System.out.println("oldPerson " + oldPerson);
        return new Book();
    }

    @Bean
    public Person person2() {
        return person();
    }
}