netCDF-Java code to aggregate grib2 files into a "best" collection

AggGrib2.java

import org.jdom2.Element;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;

import thredds.featurecollection.FeatureCollectionConfig;
import thredds.featurecollection.FeatureCollectionType;
import ucar.nc2.dataset.NetcdfDataset;
import ucar.nc2.grib.collection.GribCdmIndex;
import ucar.nc2.grib.collection.GribCollectionImmutable;

/**
 * Created by sarms on 1/5/17.
 */
public class AggGrib2 {
    final static Logger exampleLogger = LoggerFactory.getLogger(AggGrib2.class);

    public static void main(String[] args) {
        // the directory where the grib2 files that you wish to aggregate live
        String dataDir = "/Users/sarms/Desktop/gribAgg/grib2/";
        // the is the name of the collection - it can be whatever you like, just don't use spaces
        String name = "GribAgg";
        String collectionName = "GribAgg_Collection";

        // basically a regex used to locate your grib files
        String spec = dataDir + ".*grib2$";
        //  
        FeatureCollectionType fcType = FeatureCollectionType.GRIB2;
        // don't worry about these for now
        String timePartition = "file";
        String dateFormatMark = null;
        String olderThan = null;
        Element innerNcml = null;
        String path = ""; 

        // aggregation magic
    
        FeatureCollectionConfig fcc = new FeatureCollectionConfig(name, path, fcType, spec,
                collectionName, dateFormatMark, olderThan, timePartition, innerNcml);
    
        try (GribCollectionImmutable gc = GribCdmIndex.openGribCollection(fcc, null, exampleLogger)) {
            GribCollectionImmutable.Dataset ds = gc.getDatasetByTypeName("Best");
            String fullCollectionIndexFilePath = dataDir + name + ".ncx3";
            // now we open the collection index file, which catalogs all of the grib 
            //  records in your collection
            NetcdfDataset ncd = gc.getNetcdfDataset(ds, ds.getGroup(0), fullCollectionIndexFilePath,
                                                    fcc, null, exampleLogger);
            System.out.println(ncd.getVariables());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}