code: public String get_senders(Map<String, String> data) {
          String option = data.get("option");
          String url;
          if (EMPTY_STRING.equals(option)) {
              url = "advanced/";
          }
          else {
              url = "advanced/option/" + option + "/";
          }
          return get(url, EMPTY_STRING);
      }
docs: /*
  Get Access of created senders information.
  @param {Object} data contains json objects as a key value pair from HashMap.
  @options data {String} option: Options to get senders. Possible options – IP-wise, & Domain-wise ( only for dedicated IP clients ). Example: to get senders with specific IP, use $option=’1.2.3.4′, to get senders with specific domain use, $option=’domain.com’, & to get all senders, use $option="" [Optional]