public TopNMetric(String metricName){
  this.type=TopNMetricType.NUMERIC;
  this.metricName=Optional.of(metricName);
  this.nested=Optional.empty();
  this.previousStop=Optional.empty();
}

public TopNMetric ( String metricName ) { this . type = TopNMetricType . NUMERIC ; this . metricName = Optional . of ( metricName ) ; this . nested = Optional . empty ( ) ; this . previousStop = Optional . empty ( ) ; }
constructs a numeric sort of the given metric with default sorting order ( descending ) .
