code: public Map<String, String> build(SignType signType) throws Exception {
  		Map<String, String> map = createMap();
  		if(SignType.MD5 == signType) {
  			map.put("sign_type", "MD5");
  		}else {
  			map.put("sign_type", "HMAC-SHA256");
  		}
  		map.put("sign", PaymentKit.createSign(map, getPaternerKey(), signType));
  		return map;
  	}
docs: 构建请求参数
  
  @param signType
  @return Map<String, String>
  @throws Exception