code: @Override
  	public String getMassPrintURL(String CorpNum, int ItemCode,
  			String[] MgtKeyList) throws PopbillException {
  		return getMassPrintURL(CorpNum, ItemCode, MgtKeyList, null);
  	}
docs: /*
  (non-Javadoc)
  @see com.popbill.api.StatementService#getMassPrintURL(java.lang.String, int, java.lang.String[])