public long getSyncDelayMillis() {
        return syncDelayMillis;
    }
@Test
    void testUpgradeConfig() throws InterruptedException {
        assertEquals(DistroConstants.DEFAULT_DATA_SYNC_DELAY_MILLISECONDS, distroConfig.getSyncDelayMillis());
        MockEnvironment environment = new MockEnvironment();
        environment.setProperty(DistroConstants.DATA_SYNC_DELAY_MILLISECONDS, String.valueOf(syncDelayMillis));
        EnvUtil.setEnvironment(environment);
        NotifyCenter.publishEvent(ServerConfigChangeEvent.newEvent());
        TimeUnit.SECONDS.sleep(1);
        assertEquals(syncDelayMillis, distroConfig.getSyncDelayMillis());
    }