StopWatch(Clock clock) {
        this.clock = clock;
        this.startTime = clock.instant();
    }
@Test
    public void testStopWatch() {
        MockClock mockClock = MockClock.at(2019, 1, 1, 12, 0, 0, ZoneId.of("UTC"));

        StopWatch watch = new StopWatch(mockClock);

        mockClock.advanceBy(Duration.ofSeconds(5));

        Duration duration = watch.stop();
        LOG.info(watch.toString());
        assertThat(duration.getSeconds()).isEqualTo(5);
    }