public static String finalSigningKeyString(String secret, String date, String region, String productCode,
            String signMethod) {
        return Base64.getEncoder().encodeToString(finalSigningKey(secret, date, region, productCode, signMethod));
    }
@Test
    void testFinalSigningKeyStringWithException() {
        assertThrows(RuntimeException.class,
                () -> CalculateV4SigningKeyUtil.finalSigningKeyString("", "2021-01-01", "cn-hangzhou",
                        RamConstants.SIGNATURE_V4_PRODUCE, "non-exist"));
    }