Spring Boot 2.0.x - @Configuration class @Autowired entityManagerFactory NullPointerException

Question

I used Hibernate session to query data from MySQL. I used JPA EntityManagerFactory to get Hibernate SessionFactory:

@Configuration
public class DatabaseConfig {

    @Autowired
    private EntityManagerFactory entityManagerFactory;

    @Bean
    public SessionFactory getSessionFactory() {
        if (entityManagerFactory.unwrap(SessionFactory.class) == null) {
            throw new NullPointerException("Factory is not a hibernate factory");
        }
        return entityManagerFactory.unwrap(SessionFactory.class);
    }
}

This worked fine with Spring Boot 1.5.x. But when I updated Spring Boot to 2.0.1:

Error creating bean with name 'databaseConfig': Unsatisfied dependency expressed through field 'entityManagerFactory';

What should I do to solve this problem in Spring Boot 2.0.x?