public Histogram histogram(String name) {
        return getOrAdd(name, MetricBuilder.HISTOGRAMS);
    }
@Test
    public void accessingAHistogramRegistersAndReusesIt() {
        final Histogram histogram1 = registry.histogram("thing");
        final Histogram histogram2 = registry.histogram("thing");

        assertThat(histogram1)
                .isSameAs(histogram2);

        verify(listener).onHistogramAdded("thing", histogram1);
    }