// Test constants are not modifiable (ensure they're final)
    public void test_constantsAreImmutable() throws Exception {
        Field originField = CorsHandler.class.getDeclaredField("ACCESS_CONTROL_ALLOW_ORIGIN");
        assertTrue("ACCESS_CONTROL_ALLOW_ORIGIN should be final", Modifier.isFinal(originField.getModifiers()));

        Field headersField = CorsHandler.class.getDeclaredField("ACCESS_CONTROL_ALLOW_HEADERS");