wellKnownProtectedResourceUrl method
The RFC 9728 well-known PRM URL tried first when a 401 carries no
resource_metadata=: at the resource's path
(https://api.example.com/.well-known/oauth-protected-resource/mcp);
the root follows (see protectedResourceMetadataUrls).
Implementation
Uri wellKnownProtectedResourceUrl(String resourceUrl) =>
protectedResourceMetadataUrls(resourceUrl).first;