}

    @Test
    public void test_nullMessage() {
        final LlmException exception = new LlmException(null);
        assertNull(exception.getMessage());
    }

    @Test
    public void test_emptyMessage() {
        final LlmException exception = new LlmException("");
        assertEquals("", exception.getMessage());
    }

    @Test
    public void test_constructorWithMessageDefaultsToUnknownErrorCode() {

        // Verify cause chain
        assertEquals(middleCause, exception.getCause());
        assertEquals(rootCause, exception.getCause().getCause());
    }

    @Test
    public void test_emptyMessage() {
        // Setup
        final String message = "";
        final VaMessenger<FessMessages> messageCode = messages -> messages.addErrorsSsoLoginError(UserMessages.GLOBAL_PROPERTY_KEY);

        // Execute

        // Verify cause chain is preserved
        assertEquals(middleCause, exception.getCause());
        assertEquals(rootCause, exception.getCause().getCause());
    }

    @Test
    public void test_emptyMessage() {
        // Setup
        final String message = "";
        final VaMessenger<FessMessages> messageCode = messages -> messages.addErrorsInvalidQueryUnknown(UserMessages.GLOBAL_PROPERTY_KEY);

        // Execute