Duende.AspNetCore.Authentication.OAuth2Introspection 7.0.2

This patch release fixes concurrent requests with the same token failing because of another request's introspection call.

• When several requests with the same token arrived together, they shared one introspection call, and if that call failed, every waiting request failed with it. A request that had joined just before the backchannel HttpClient timeout could fail almost immediately with another request's timeout. Now only the request that started the call gets that failure, and each request that was waiting retries once with a call of its own. Errors returned by the introspection endpoint, and network errors, are still shared as before. #341 (fixes #281)
• Introspection now respects client disconnects. If the client of the request that started an introspection call disconnects, the call is cancelled and any requests waiting on it make their own call. A request whose client disconnects while it waits on another request's call stops waiting. Before this release, the introspection call always ran to completion. #341

This release targets .NET 8, .NET 9 and .NET 10.