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