apollo-biz/src/main/java/com/ctrip/framework/apollo/biz/service/InstanceService.java/InstanceService/updateInstanceConfig
class InstanceService:  @Transactional
  public InstanceConfig updateInstanceConfig(InstanceConfig instanceConfig) {
    InstanceConfig existedInstanceConfig = instanceConfigRepository.findById(instanceConfig.getId()).orElse(null);
    Preconditions.checkArgument(existedInstanceConfig != null, String.format(
        "Instance config %d doesn't exist", instanceConfig.getId()));

    existedInstanceConfig.setConfigClusterName(instanceConfig.getConfigClusterName());
    existedInstanceConfig.setReleaseKey(instanceConfig.getReleaseKey());
    existedInstanceConfig.setReleaseDeliveryTime(instanceConfig.getReleaseDeliveryTime());
    existedInstanceConfig.setDataChangeLastModifiedTime(instanceConfig
        .getDataChangeLastModifiedTime());

    return instanceConfigRepository.save(existedInstanceConfig);
  }