public static String unhash(int port)
    {
        return unhash(new StringBuilder(), port, 'z').toString();
    }
@Test
    public void testUnhash()
    {
        // theoretically up to 65535 but let's be greedy and waste 10 ms
        for (int port = 0; port < 100_000; ++port) {
            String hash = Utils.unhash(port);
            assertThat(hash, notNullValue());
            assertThat(hash.hashCode(), is(port));
        }
    }