public static BrokerConfig getBrokerConfig() {
        if (brokerConfig == null) {
            throw new IllegalArgumentException("brokerConfig Cannot be null !");
        }
        return brokerConfig;
    }
@Test(expected = IllegalArgumentException.class)
    public void getBrokerConfig_NullConfiguration_ThrowsException() {
        BrokerConfigSingleton.getBrokerConfig();
    }