apollo-client-config-data/src/main/java/com/ctrip/framework/apollo/config/data/importer/ApolloConfigDataLoaderInitializer.java/ApolloConfigDataLoaderInitializer/initApolloClientInternal
class ApolloConfigDataLoaderInitializer:  private void initApolloClientInternal() {
    new ApolloClientSystemPropertyInitializer(this.log)
        .initializeSystemProperty(this.binder, this.bindHandler);
    new ApolloClientExtensionInitializeFactory(this.log,
        this.bootstrapContext).initializeExtension(this.binder, this.bindHandler);
    DeferredLogger.enable();
    ApolloConfigDataInjectorCustomizer.register(ConfigFactory.class,
        PureApolloConfigFactory::new);
  }