apollo-client/src/main/java/com/ctrip/framework/apollo/spring/config/PropertySourcesProcessor.java/PropertySourcesProcessor/postProcessBeanFactory
class PropertySourcesProcessor:  @Override
  public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
    this.configUtil = ApolloInjector.getInstance(ConfigUtil.class);
    initializePropertySources();
    initializeAutoUpdatePropertiesFeature(beanFactory);
  }