WebApplication does not react to appsettings.json changes

[halter73]

Describe the bug

Starting in rc2, WebApplicationBuilder indirectly disposes IConfigurationProviders that are still in use by WebApplication. For FileConfigurationProviders, this prevents IConfigurationProvider.GetReloadToken() from firing. This means changes to configuration sources like appsettings.json are not observed after the WebApplication is built.

To Reproduce

Run the following commands:

> dotnet new globaljson --sdk-version 6.0.100-rc.2.21472.38
> dotnew new web
> dotnet run

While the application is running, change "Microsoft.AspNetCore": "Warning" to "Microsoft.AspNetCore": "Information" and make a request.

Expected output:

C:\dev\halter73\MinimalPlayground master ≢  ~1 ❯ dotnet run
Building...
info: Microsoft.Hosting.Lifetime[14]
      Now listening on: https://localhost:7159
info: Microsoft.Hosting.Lifetime[14]
      Now listening on: http://localhost:5016
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
      Content root path: C:\dev\halter73\MinimalPlayground
dbug: Microsoft.AspNetCore.Server.Kestrel[0]
      Config reload token fired. Checking for changes...
dbug: Microsoft.AspNetCore.Server.Kestrel.Connections[39]
      Connection id "0HMC22SP3DB29" accepted.
dbug: Microsoft.AspNetCore.Server.Kestrel.Connections[1]
      Connection id "0HMC22SP3DB29" started.
dbug: Microsoft.AspNetCore.Server.Kestrel.Https.Internal.HttpsConnectionMiddleware[3]
      Connection 0HMC22SP3DB29 established using the following protocol: Tls12
info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
      Request starting HTTP/2 GET https://localhost:7159/ - -
...

Actual output:

> dotnet run
Building...
info: Microsoft.Hosting.Lifetime[14]
      Now listening on: https://localhost:7159
info: Microsoft.Hosting.Lifetime[14]
      Now listening on: http://localhost:5016
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
      Content root path: C:\dev\halter73\MinimalPlayground