public static boolean isCoreRequest(HeaderMap headers) {
        return headers.contains(ORIGIN)
                || headers.contains(ACCESS_CONTROL_REQUEST_HEADERS)
                || headers.contains(ACCESS_CONTROL_REQUEST_METHOD);
    }
@Test
    public void testIsCoreRequest() {
        HeaderMap headers = new HeaderMap();
        assertThat(CorsUtil.isCoreRequest(headers), is(false));
        headers = new HeaderMap();
        headers.add(ORIGIN, "");
        assertThat(CorsUtil.isCoreRequest(headers), is(true));
        headers = new HeaderMap();
        headers.add(ACCESS_CONTROL_REQUEST_HEADERS, "");
        assertThat(CorsUtil.isCoreRequest(headers), is(true));
        headers = new HeaderMap();
        headers.add(ACCESS_CONTROL_REQUEST_METHOD, "");
        assertThat(CorsUtil.isCoreRequest(headers), is(true));
    }