@Test
public void accessingACustomHistogramRegistersAndReusesIt() {

    final MetricRegistry.MetricSupplier<Histogram> supplier = () -> histogram;
    final Histogram histogram1 = registry.histogram("thing", supplier);
    final Histogram histogram2 = registry.histogram("thing", supplier);
    assertThat(histogram1)
            .isSameAs(histogram2);
    verify(listener).onHistogramAdded("thing", histogram1);
}