@Override
    public void removeNetwork(String netId) {
        checkArgument(!Strings.isNullOrEmpty(netId), ERR_NULL_NETWORK_ID);
        synchronized (this) {
            if (isNetworkInUse(netId)) {
                final String error = String.format(MSG_NETWORK, netId, ERR_IN_USE);
                throw new IllegalStateException(error);
            }
            Network osNet = osNetworkStore.removeNetwork(netId);
            if (osNet != null) {
                log.info(String.format(MSG_NETWORK, deriveResourceName(osNet), MSG_REMOVED));
            }

            Versioned<OpenstackNetwork> augmentedNetwork = augmentedNetworkMap.remove(netId);
            if (augmentedNetwork != null) {
                log.info(String.format(MSG_NETWORK_TYPE,
                                    augmentedNetwork.value().type(), MSG_REMOVED));
            }
        }
    }
@Test(expected = IllegalArgumentException.class)
    public void testRemoveNetworkWithNull() {
        target.removeNetwork(null);
    }