code: func OAuth2ClientCredentials(clientID, clientSecret, tokenURL string) registry.Option {
  	return func(o *registry.Options) {
  		c := clientcredentials.Config{
  			ClientID:     clientID,
  			ClientSecret: clientSecret,
  			TokenURL:     tokenURL,
  		}
  
  		o.Context = context.WithValue(o.Context, contextHttpClient{}, newOAuthClient(c))
  	}
  }
docs: // Enable OAuth 2.0 Client Credentials Grant Flow