public void clear() {
        for (int i = 0; i < sections.length; i++) {
            sections[i].clear();
        }
    }
@Test
    public void testClear() {
        ConcurrentOpenHashSet<String> set =
                ConcurrentOpenHashSet.<String>newBuilder()
                .expectedItems(2)
                .concurrencyLevel(1)
                .autoShrink(true)
                .mapIdleFactor(0.25f)
                .build();
        assertEquals(set.capacity(), 4);

        assertTrue(set.add("k1"));
        assertTrue(set.add("k2"));
        assertTrue(set.add("k3"));

        assertEquals(set.capacity(), 8);
        set.clear();
        assertEquals(set.capacity(), 4);
    }