cdm/src/main/java/ucar/nc2/ft/point/StationTimeSeriesCollectionImpl.java
@Override
  public PointFeatureCollection flatten(List<String> stationNames, CalendarDateRange dateRange, List<VariableSimpleIF> varList) throws IOException {
    if ((stationNames == null) || (stationNames.size() == 0))
      return new StationTimeSeriesCollectionFlattened(this, dateRange);

    List<StationFeature> subsetStations = getStationHelper().getStationFeaturesFromNames(stationNames);
    return new StationTimeSeriesCollectionFlattened(new StationSubset(this, subsetStations), dateRange);
  }
@Override
  public PointFeatureCollection flatten(List<String> stationNames, CalendarDateRange dateRange, List<VariableSimpleIF> varList) throws IOException {
    if ((stationNames == null) || (stationNames.size() == 0))
      return new StationTimeSeriesCollectionFlattened(this, dateRange);

    List<StationFeature> subsetStations = getStationHelper().getStationFeaturesFromNames(stationNames);
    return new StationTimeSeriesCollectionFlattened(new StationSubset(this, subsetStations), dateRange);
  }
might need to override for efficiency