UserPicker doesn't set current user in UseSampleMvc.AspNetCore

[joopscheer]

The sample doesn't set the current user. The user picker always displays the anonymous user as the selected/picked user.

After some investigation I identified the problem. The user picker is determines the current user based on the current principal identity name. In the sample the added users don't have a name. I fixed this in a local branch and would love to provide you with a PR.

Wouldn't it be better to add a claim for the name of the StuntmanUser within the constructor? The DefaultNameClaimType is name by default anyway.