public void testFromParts() {
    HostAndPort hp = HostAndPort.fromParts("gmail.com", 81);
    assertEquals("gmail.com", hp.getHost());
    assertTrue(hp.hasPort());
    assertEquals(81, hp.getPort());

    assertThrows(IllegalArgumentException.class, () -> HostAndPort.fromParts("gmail.com:80", 81));

    assertThrows(IllegalArgumentException.class, () -> HostAndPort.fromParts("gmail.com", -1));
  }

  public void testFromHost() {