### Question:
MetricUtils { @VisibleForTesting static void instantiateNonHeapMemoryMetrics(final MetricGroup metricGroup) { instantiateMemoryUsageMetrics(metricGroup, () -> ManagementFactory.getMemoryMXBean().getNonHeapMemoryUsage()); } private  MetricUtils(); static JobManagerMetricGroup instantiateJobManagerMetricGroup(
			final MetricRegistry metricRegistry,
			final String hostname,
			final Optional<Time> systemResourceProbeInterval); static TaskManagerMetricGroup instantiateTaskManagerMetricGroup(
			MetricRegistry metricRegistry,
			TaskManagerLocation taskManagerLocation,
			NetworkEnvironment network,
			Optional<Time> systemResourceProbeInterval); static void instantiateStatusMetrics(
			MetricGroup metricGroup); static ActorSystem startMetricsActorSystem(Configuration configuration, String hostname, Logger logger);  }### Answer:
@Test public void testNonHeapMetricsCompleteness() { final InterceptingOperatorMetricGroup nonHeapMetrics = new InterceptingOperatorMetricGroup(); MetricUtils.instantiateNonHeapMemoryMetrics(nonHeapMetrics); Assert.assertNotNull(nonHeapMetrics.get(MetricNames.MEMORY_USED)); Assert.assertNotNull(nonHeapMetrics.get(MetricNames.MEMORY_COMMITTED)); Assert.assertNotNull(nonHeapMetrics.get(MetricNames.MEMORY_MAX)); }