if metric.Histogram == nil {
				return true
			}
			for k, v := range metric.Histogram {
				labels = append(labels, metric.HistogramBucketLabel)
				values = append(values, k)
				ch <- prometheus.MustNewConstMetric(
					prometheus.NewDesc(
						prometheus.BuildFQName(string(metric.Description.Namespace),
							string(metric.Description.Subsystem),
							string(metric.Description.Name)),
						metric.Description.Help,