code: public void addDatapoints(Map<Long, Double> datapoints) {
  		if (datapoints != null) {
  			_datapoints.putAll(datapoints);
  		}
  	}
docs: Adds the current set of data points to the current set.
  
  @param  datapoints  The set of data points to add. If null or empty, only the deletion of the current set of data points is performed.