code: public String send_bat_sms(Map<String, Object> data) {
          String id = data.get("id").toString();
          String to = data.get("to").toString();
          Gson gson = new Gson();
          String json = gson.toJson(data);
          return get("sms/" + id + "/" + to, EMPTY_STRING);
      }
docs: /*
  Send a Test SMS.
  @param {Object} data contains json objects as a key value pair from HashMap.
  @options data {Integer} id: Id of the SMS campaign [Mandatory]
  @options data {String} to: Mobile number with the country code to send test SMS. The mobile number defined here should belong to one of your contacts in SendinBlue account and should not be blacklisted [Mandatory]