@Test
public void testSingleton() {

    DnsServerAddresses seq = DnsServerAddresses.singleton(ADDR1);
    // Should return the same iterator instance for least possible footprint.
    assertThat(seq.stream(), is(sameInstance(seq.stream())));
    DnsServerAddressStream i = seq.stream();
    assertNext(i, ADDR1);
    assertNext(i, ADDR1);
    assertNext(i, ADDR1);
}