public Map<String,String> toParameterMap()
  {
    Map<String,String> parameters = new LinkedHashMap<String,String>();
    parameters.put("merchant_id",getMerchantId());
    if (GoCoin.hasValue(getStatus()))
    {
      parameters.put("status",getStatus());
    }
    if (GoCoin.hasValue(getStartTs()))
    {
      parameters.put("start_time",getStartTsString());
    }
    if (GoCoin.hasValue(getEndTs()))
    {
      parameters.put("end_time",getEndTsString());
    }
    if (GoCoin.hasValue(getPageNumber()))
    {
      parameters.put("page_number",getPageNumber());
    }
    if (GoCoin.hasValue(getPerPage()))
    {
      parameters.put("per_page",getPerPage());
    }
   return parameters;
  }