code: @Override
      public MessageBriefInfo[] getStates(String corpNum, String[] receiptNumList, String userID)
              throws PopbillException {
          if (receiptNumList == null || receiptNumList.length == 0)
              throw new PopbillException(-99999999, "접수번호 목록이 입력되지 않았습니다.");
  
          String PostData = toJsonString(receiptNumList);
  
          return httppost("/Message/States", corpNum, PostData, userID, MessageBriefInfo[].class);
      }
docs: /*
  (non-Javadoc)
  @see com.popbill.api.MessageService#getStates(java.lang.String, java.lang.String[], java.lang.String)