bucketMGMap map[collectorPath]*MetricsGroup

	// Gatherers for non-bucket MetricsGroup's
	mgGatherers map[collectorPath]prometheus.Gatherer

	collectorPaths []collectorPath
}

func newMetricGroups(r *prometheus.Registry) *metricsV3Collection {
	// Create all metric groups.
	apiRequestsMG := NewMetricsGroup(apiRequestsCollectorPath,
		[]MetricDescriptor{
			apiRejectedAuthTotalMD,
			apiRejectedHeaderTotalMD,

	registry := prometheus.NewRegistry()
	authFn := AuthMiddleware
	if authType == prometheusPublic {
		authFn = NoAuthMiddleware
	}

	metricGroups := newMetricGroups(registry)

	return &metricsV3Server{
		registry: registry,
		opts: promhttp.HandlerOpts{
			ErrorLog:            promLogger{},
			ErrorHandling:       promhttp.HTTPErrorOnError,
			Registry:            registry,