public String toGetParam(final String json) {
        if (StringUtils.isBlank(json)) {
            return EMPTY;
        }
        final Map<String, String> map = toStringMap(json);
        StringBuilder stringBuilder = new StringBuilder();
        map.forEach((k, v) -> {
            try {
                stringBuilder.append(k)
                        .append(EQUAL_SIGN)
                        .append(URLDecoder.decode(v, Constants.DECODE))
                        .append(AND);
            } catch (UnsupportedEncodingException e) {
                LOG.error("decode:{} failed !", v, e);
            }
        });
        final String r = stringBuilder.toString();
        return r.substring(0, r.lastIndexOf(AND));
        
    }
to Get Param.

@param json json
@return java.lang.String string
shenyu-common/src/main/java/org/apache/shenyu/common/utils/GsonUtils.java