apollo-client/src/main/java/com/ctrip/framework/apollo/internals/RemoteConfigRepository.java/RemoteConfigRepository/getConfigServices
class RemoteConfigRepository:  private List<ServiceDTO> getConfigServices() {
    List<ServiceDTO> services = m_serviceLocator.getConfigServices();
    if (services.size() == 0) {
      throw new ApolloConfigException("No available config service");
    }

    return services;
  }