title: Is it possible to create a Blazor Server Multi-tenant app that authenticates with microsoft Identity?
body: <p>I have created a Blazor Server side app that requires multi tenant authentication.  I have added a clientId column to the data tables, that will be used for data separation between clients (tenants).
  I dont want to create my own login and authentication provider, as I'm worried it wont be secure.  However, I cant see any way to get the user Id after login,  so I have no idea how to get a users ClientId. I could use the Identity.name property,  but that is no good if there are users with duplicate names.
  Do I need to create custom login / user registration?</p>