// Expected exception
            assertNotNull(e);
        }
    }

    // Test special characters in property values
    @Test
    public void test_get_specialCharacters() {
        String testKey = "special.chars";
        String specialValue = "!@#$%^&*()_+-=[]{}|;':\",./<>?";
        System.setProperty(Constants.FESS_CONFIG_PREFIX + testKey, specialValue);

        try {