code: public static Map<String, String> prepayIdCreateSign(String prepay_id) {
  		Map<String, String> packageParams = new HashMap<String, String>();
  		packageParams.put("appId", WxPayApiConfigKit.getWxPayApiConfig().getAppId());
  		packageParams.put("timeStamp", String.valueOf(System.currentTimeMillis() / 1000));
  		packageParams.put("nonceStr", String.valueOf(System.currentTimeMillis()));
  		packageParams.put("package", "prepay_id=" + prepay_id);
  		packageParams.put("signType", "MD5");
  		String packageSign = PaymentKit.createSign(packageParams,
  				WxPayApiConfigKit.getWxPayApiConfig().getPaternerKey());
  		packageParams.put("paySign", packageSign);
  		return packageParams;
  	}
docs: 预付订单再次签名
  
  @param prepay_id
  @return <Map<String, String>>