@Test
  public void testGetInstanceNoHadoopCompat() throws Exception {
    assertThat(CompatibilitySingletonFactory.getInstance(MetricsRESTSource.class),
      instanceOf(MetricsRESTSourceImpl.class));
  }
Test of Rest Metrics Source interface.
hbase-hadoop-compat/src/test/java/org/apache/hadoop/hbase/rest/TestMetricsRESTSource.java