public JvmMetrics getJvmMetrics() {
    return jvmMetrics;
  }
@Test
  public void testReferenceOfSingletonJvmMetrics()  {
    JvmMetrics jvmMetrics = JvmMetrics.initSingleton("NodeManagerModule", null);
    Assert.assertEquals("NodeManagerMetrics should reference the singleton" +
        " JvmMetrics instance", jvmMetrics, metrics.getJvmMetrics());
  }