code: func (o CustomResourceDefinitionsServerOptions) Config() (*apiserver.Config, error) {
  	// TODO have a "real" external address
  	if err := o.RecommendedOptions.SecureServing.MaybeDefaultWithSelfSignedCerts("localhost", nil, []net.IP{net.ParseIP("127.0.0.1")}); err != nil {
  		return nil, fmt.Errorf("error creating self-signed certificates: %v", err)
  	}
  
  	serverConfig := genericapiserver.NewRecommendedConfig(apiserver.Codecs)
  	if err := o.RecommendedOptions.ApplyTo(serverConfig); err != nil {
  		return nil, err
  	}
  	if err := o.APIEnablement.ApplyTo(&serverConfig.Config, apiserver.DefaultAPIResourceConfigSource(), apiserver.Scheme); err != nil {
  		return nil, err
  	}
  
  	config := &apiserver.Config{
  		GenericConfig: serverConfig,
  		ExtraConfig: apiserver.ExtraConfig{
  			CRDRESTOptionsGetter: NewCRDRESTOptionsGetter(*o.RecommendedOptions.Etcd),
  			ServiceResolver:      &serviceResolver{serverConfig.SharedInformerFactory.Core().V1().Services().Lister()},
  			AuthResolverWrapper:  webhook.NewDefaultAuthenticationInfoResolverWrapper(nil, serverConfig.LoopbackClientConfig),
  		},
  	}
  	return config, nil
  }
docs: // Config returns an apiextensions-apiserver configuration.