code: public void addDataPointSet(String series, Set<DataPoint> dataPoints) {
          DataSet set = store.get(series);
          if (set == null) {
              set = new DataSet(dataPoints);
              store.put(series, set);
          } else {
              set.addAll(dataPoints);
          }
      }
docs: Adds a set of `DataPoint`s to a series.
  
  @param series     The series the DataPoints should be added to. If the series doesn't exist,
  it will be created.
  @param dataPoints Data to be added.