public int incrementAndGet() {
        Integer index = this.threadLocalIndex.get();
        if (null == index) {
            index = random.nextInt();
        }
        this.threadLocalIndex.set(++index);
        return index & POSITIVE_MASK;
    }
@Test
    public void testIncrementAndGet() throws Exception {
        ThreadLocalIndex localIndex = new ThreadLocalIndex();
        int initialVal = localIndex.incrementAndGet();

        assertThat(localIndex.incrementAndGet()).isEqualTo(initialVal + 1);
    }