使用lamda提取集合中元素为集合的属性
List<RoomOrderModifyGuestForm> orderRoomGuestList = new LinkedList<>();
orderRoomForm.getOrderRoomNoInfo().stream()
.filter(orderRoomNoInfoForm -> CollectionUtils.isNotEmpty(orderRoomNoInfoForm.getGuestInfoFormList()))
.map(OrderRoomNoInfoForm::getGuestInfoFormList)
.forEach(orderRoomGuestList::addAll);
