static int bucketMinUs(int bucket) {
        return bucket == 0 ? 0 : 1 << bucket;
    }
@Test
    public void bucketMinUs() {
        assertEquals(0, LatencyDistribution.bucketMinUs(0));
        assertEquals(2, LatencyDistribution.bucketMinUs(1));
        assertEquals(4, LatencyDistribution.bucketMinUs(2));
        assertEquals(8, LatencyDistribution.bucketMinUs(3));
        assertEquals(16, LatencyDistribution.bucketMinUs(4));
        assertEquals(32, LatencyDistribution.bucketMinUs(5));
    }