This is good to know, but there are two issues: first, these code-gaps on the demo-site are *everywhere*, ever since it was redone (when the old, default ASPX examples were dumped). This is glaring hole. It makes the demo site almost useless, because key pieces of code, without which the example will not function, are missing. Further, there is no pointer on the demo site that even addresses this lacuna, or points to the Sample Application.
Second issue: the sample application is out of date. It hasn't been updated since July 2016, it hasn't been renamed from "MVC 6" to "Core", the instructions require VS 2015, etc. I'll clone it so that I can look at the code, but will it really be usable as an example project that I can "play" with? There have been a lot of changes in project structure since then.