private void handleRefresh(Set<IFileData> oldfiles) {
   IvyXmlWriter xw = pybase_main.beginMessage("RESOURCE");
   int ctr = 0;
   for (IFileData fd : all_files) {
     IFileData old = null;
     for (IFileData ofd : oldfiles) {
       if (ofd.getFile().equals(fd.getFile())) {
         old = ofd;
         break;
       }
     }
     if (old == null) {
       outputDelta(xw, "ADDED", fd);
       ++ctr;
     } else if (old.getLastDateLastModified() != fd.getLastDateLastModified()) {
       oldfiles.remove(old);
       outputDelta(xw, "CHANGED", fd);
       ++ctr;
     } else {
       oldfiles.remove(old);
     }
   }
   for (IFileData fd : oldfiles) {
     outputDelta(xw, "REMOVED", fd);
     ++ctr;
   }
   if (ctr > 0) {
     pybase_main.finishMessage(xw);
   }
 }