public static HazelcastInstance newHazelcastClient() {
        return newHazelcastClientInternal(resolveClientConfig(null), null, null, null);
    }
@Test(expected = InvalidConfigurationException.class)
    public void testNewHazelcastClient_withSameConfig() {
        String instanceName = randomString();
        ClientConfig config = new ClientConfig();
        config.setInstanceName(instanceName);

        HazelcastClient.newHazelcastClient(config);
        HazelcastClient.newHazelcastClient(config);
    }