code: public static List<String> getVariantSetIds(String datasetId, OfflineAuth auth)
        throws IOException {
      List<String> output = Lists.newArrayList();
      Genomics genomics = GenomicsFactory.builder().build().fromOfflineAuth(auth);
      Iterable<VariantSet> vs = Paginator.Variantsets.create(genomics)
          .search(new SearchVariantSetsRequest().setDatasetIds(Lists.newArrayList(datasetId)),
              "variantSets(id),nextPageToken");
      for (VariantSet v : vs) {
        output.add(v.getId());
      }
      if (output.isEmpty()) {
        throw new IOException("Dataset " + datasetId + " does not contain any VariantSets");
      }
      return output;
    }
docs: Gets VariantSetIds from a given datasetId using the Genomics API.
  
  @param datasetId The id of the dataset to query.
  @param auth The OfflineAuth for the API request.
  @return The list of variantSetIds in the dataset.
  @throws IOException If dataset does not contain any variantSets.