code: func (sink *influxdbSink) GetMetricNames(metricKey core.HistoricalKey) ([]string, error) {
  	if err := sink.checkSanitizedKey(&metricKey); err != nil {
  		return nil, err
  	}
  	return sink.stringListQuery(fmt.Sprintf("SHOW MEASUREMENTS WHERE %s", sink.keyToSelector(metricKey)), "Unable to list available metrics")
  }
docs: // GetMetricNames retrieves the available metric names for the given object