Function exchange_code_for_provider 

pub async fn exchange_code_for_provider(
    provider: CloudProvider,
    code: &str,
    callback_state: Option<&str>,
    request: &AuthorizeRequest,
    redirect_uri: &str,
    clock: &dyn Clock,
) -> Result<OAuthTokens, OAuthError>

Exchange an authorization code captured by the host for provider’s tokens. redirect_uri, request, and callback_state must match the originating build_authorize_request_for_provider call.

Gated on oauth-providers.