public static Map<String, String> transStringMap(final Map<String, Object> map) {
        return Optional.ofNullable(map)
                .map(m -> m.entrySet().stream().collect(Collectors.toMap(Map.Entry::getKey, e -> Objects.toString(e.getValue(), null))))
                .orElse(null);
    }
@Test
    public void testTransStringMap() {
        Map<String, Object> jsonParams = new HashMap<>();
        jsonParams.put("a", 1);
        jsonParams.put("b", 2);
        Map<String, String> stringStringMap = MapUtils.transStringMap(jsonParams);
        assertEquals(stringStringMap.get("a").getClass(), String.class);
        assertEquals(stringStringMap.get("a"), "1");
    }