class PetService {
  private final Provider<PetDao> dao;

  public PetService(PetDao dao) {
    this.dao = dao;
  }

  public int numberOfPets(String name) {
    return dao.get().getNumberOfPets();
  }
}

@Configuration
class PetServiceConfiguration {
  @Bean
  @Scope(BeanDefinition.SCOPE_PROTOTYPE)
  PetDao petDao() {
    if("true".equals(System.getProperty("useV1PetDao"))) {
        return new PetDaoV1();
    } else {
        return new PetDaoV2();
    }
  }

  @Bean
  PetService petService(Provider<PetDao> provider) {
    return new PetService(provider);
  }
}