public static MonitoringInfoMetricName named(String urn, Map<String, String> labels) {
    return new MonitoringInfoMetricName(urn, labels);
  }
@Test
  public void testNullLabelsThrows() {
    thrown.expect(IllegalArgumentException.class);
    HashMap<String, String> labels = null;
    MonitoringInfoMetricName.named(MonitoringInfoConstants.Urns.ELEMENT_COUNT, labels);
  }