code: @Override
      public IssueResponse issue(String CorpNum, MgtKeyType KeyType, String MgtKey,
                            String Memo, String EmailSubject, boolean ForceIssue, String UserID)
              throws PopbillException {
          if (KeyType == null)
              throw new PopbillException(-99999999, "관리번호형태가 입력되지 않았습니다.");
          if (MgtKey == null || MgtKey.isEmpty())
              throw new PopbillException(-99999999, "관리번호가 입력되지 않았습니다.");
  
          IssueRequest request = new IssueRequest();
          request.memo = Memo;
          request.emailSubject = EmailSubject;
          request.forceIssue = ForceIssue;
  
          String PostData = toJsonString(request);
  
          return httppost("/Taxinvoice/" + KeyType.name() + "/" + MgtKey,
                  CorpNum, PostData, UserID, "ISSUE", IssueResponse.class);
      }
docs: /* (non-Javadoc)
  @see com.popbill.api.TaxinvoiceService#issue(java.lang.String, com.popbill.api.taxinvoice.MgtKeyType, java.lang.String, java.lang.String, java.lang.String, boolean, java.lang.String)