apollo-client/src/main/java/com/ctrip/framework/apollo/internals/ConfigServiceLocator.java/ConfigServiceLocator/initConfigServices
class ConfigServiceLocator:  private void initConfigServices() {
    // get from run time configurations
    List<ServiceDTO> customizedConfigServices = getCustomizedConfigService();

    if (customizedConfigServices != null) {
      setConfigServices(customizedConfigServices);
      return;
    }

    // update from meta service
    this.tryUpdateConfigServices();
    this.schedulePeriodicRefresh();
  }