apollo-configservice/src/main/java/com/ctrip/framework/apollo/configservice/wrapper/DeferredResultWrapper.java/DeferredResultWrapper/DeferredResultWrapper
class DeferredResultWrapper:  public DeferredResultWrapper(long timeoutInMilli) {
    result = new DeferredResult<>(timeoutInMilli, NOT_MODIFIED_RESPONSE_LIST);
  }