RFC9728 : www-authenticate resource_metadata url

[MonsieurRz]

Hello,
I am currently studying how mod_oauth2 can be adapted for model context protocol (MCP) authentication flow (RFC9728) and the current www-authenticate response is not compatible:

• A client makes an initial request without access token to the Resource Server
• liboauth2 returns the error and the description

For RFC9728 to work a resource_metadata=url must be specified within the www-authenticate value so the client may retrieve the Authorization Server information and authenticate.