docs: @VisibleForTesting
    static List<String> convertToLabelNames(List<LabelKey> labelKeys) {
      final List<String> labelNames = new ArrayList<String>(labelKeys.size());
      for (LabelKey labelKey : labelKeys) {
        labelNames.add(Collector.sanitizeMetricName(labelKey.getKey()));
      }
      return labelNames;
    }