@SuppressWarnings("squid:S3740")
  public Statistics currentFileStatistics(int index) {
    return firstTimeSeriesMetadata.getMeasurementStatistics(index).orElse(null);
  }
Initialize the query data source. This method should be called <b>before any other methods</b>.

@param dataSource the query data source
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/execution/operator/source/SeriesScanUtil.java