Consider replacing WebClient with HttpClient in Metadataservice

and maybe add using statements.

Also add optional support for the RP to provider their own instance of HTTPClient (because of socket control?).

Reasons to do this are listed in this SO answer: https://stackoverflow.com/questions/20530152/deciding-between-httpclient-and-webclient

[abergs]

Just briefly checked the commit.

We should really not block with .Result. See Sync over Async: https://github.com/davidfowl/AspNetCoreDiagnosticScenarios/blob/master/AsyncGuidance.md#avoid-using-taskresult-and-taskwait

[CodeTherapist]

@aseigler Hmm, that’s strange! just try to build it (perhaps dotnet restore does also help).

@abergs Creating always a new instance of the HttpClient with using statement isn’t a good idea. HttpClient is intended to be instantiated once and reused throughout the life of an application - see docs and this blog post.