public Promise<Void> gracefullyShutdownClientChannels() {
        return gracefullyShutdownClientChannels(ShutdownType.SHUTDOWN);
    }
@Test
    void connectionNeedsToBeForceClosed() throws Exception {
        String configName = "server.outofservice.close.timeout";
        AbstractConfiguration configuration = ConfigurationManager.getConfigInstance();

        try {
            configuration.setProperty(configName, "0");
            createChannels(10);
            shutdown.gracefullyShutdownClientChannels().await(10, TimeUnit.SECONDS);

            assertTrue(
                    channels.isEmpty(),
                    "All channels in group should have been force closed after the timeout was triggered");
        } finally {
            configuration.setProperty(configName, "30");
        }
    }