code: @Override
      public MessageBriefInfo[] getStates(String corpNum, String[] receiptNumList)
              throws PopbillException {
          return getStates(corpNum, receiptNumList, null);
      }
docs: /*
  (non-Javadoc)
  @see com.popbill.api.MessageService#getStates(java.lang.String, java.lang.String[])