ASP.NET WebForms自定义UserControl - base.SaveViewState（）返回null - 为什么？

I've got a custom UserControl I'm working with which hosts dynamically created controls and I'm running into an odd situation where I'm seemingly losing ViewState information. In my overridden SaveViewState method on the base.SaveViewState() call, I would expect it to return me back an object containing everything that was in ViewState, but it is instead returning null.I've got a custom UserControl I'm working with