globalMetricsV3Once           sync.Once
)

func newMetricsV3Server(auth func(h http.Handler) http.Handler) *metricsV3Server {
	registry := prometheus.NewRegistry()
	metricGroups := newMetricGroups(registry)
	globalMetricsV3Once.Do(func() {
		globalMetricsV3CollectorPaths = metricGroups.collectorPaths
	})
	return &metricsV3Server{
		registry: registry,
		opts: promhttp.HandlerOpts{

	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,