private static String getKeyPairs(String key, Object value) {
        if (value != null) {
            return "&" + key + "=" + value.toString();
        } else {
            return StringUtils.EMPTY;
        }
    }
Gets key pairs.

@param key   the key
@param value the value
@return the key pairs
registry/registry-sofa/src/main/java/com/alipay/sofa/rpc/registry/sofa/SofaRegistryHelper.java