### Question:
Invite { public Signature.SecretKey secretKey() { return secretKey; } Invite(String host, int port, Identity identity, Signature.SecretKey secretKey); String host(); int port(); Identity identity(); Signature.SecretKey secretKey(); String toCanonicalForm(); @Override String toString();  }### Answer:
@Test void invalidPort() { assertThrows( IllegalArgumentException.class, () -> new Invite("localhost", -1, Identity.random(), Signature.KeyPair.random().secretKey())); }