// toString should include provided message
        assertEquals(SMBProtocolDowngradeException.class.getName() + ": " + message, ex.toString());
    }

    @Test
    void messageAndCauseConstructor_acceptsNullMessage_edgeCase() {
        // Arrange
        Throwable cause = new RuntimeException("root cause");

        // Act
        SMBProtocolDowngradeException ex = new SMBProtocolDowngradeException(null, cause);