public String getKeyColumnsAsString() throws XavaException {
   StringBuffer r = new StringBuffer();
   Collection columns = new HashSet();
   for (Iterator it = getMetaModel().getAllKeyPropertiesNames().iterator(); it.hasNext(); ) {
     String pr = (String) it.next();
     String column = getColumn(pr);
     if (columns.contains(column)) continue;
     columns.add(column);
     r.append(column);
     r.append(' ');
   }
   return r.toString().trim();
 }
 private InputStream getReport(
     HttpServletRequest request,
     HttpServletResponse response,
     Tab tab,
     TableModel tableModel,
     Integer columnCountLimit)
     throws ServletException, IOException {
   StringBuffer suri = new StringBuffer();
   suri.append("/xava/jasperReport");
   suri.append("?language=");
   suri.append(Locales.getCurrent().getLanguage());
   suri.append("&widths=");
   suri.append(Arrays.toString(getWidths(tableModel)));
   if (columnCountLimit != null) {
     suri.append("&columnCountLimit=");
     suri.append(columnCountLimit);
   }
   response.setCharacterEncoding(XSystem.getEncoding());
   return Servlets.getURIAsStream(request, response, suri.toString());
 }