public static InetAddress getLocalAddress(String... preferredNetworks) {
        if (LOCAL_ADDRESS != null) {
            return LOCAL_ADDRESS;
        }
        InetAddress localAddress = getLocalAddress0(preferredNetworks);
        LOCAL_ADDRESS = localAddress;
        return localAddress;
    }
@Test
    public void testGetLocalAddress() {
        assertThat(NetUtil.getLocalAddress()).isNotNull();
    }