### Question:
CompositeMetric implements ClusterMetric { @Override public long count() { return clusterMetrics.stream().map(ClusterMetric::count).reduce(Long::sum).orElse(0L); } CompositeMetric(ClusterMetric ... clusterMetric);  CompositeMetric(ClusterMetric clusterMetric, Iterable<ClusterMetric> clusterMetrics);  CompositeMetric(Iterable<ClusterMetric> clusterMetrics); @Override double value(); @Override long count(); @Override double min(); @Override double max(); @Override double mean(); @Override String toString();  }### Answer:
@Test public void count() { assertEquals(3L, compositeMetric.count()); }