private void AddUnpublishedData(ref Wiki actualWiki, ref Wiki unpublishedWiki)
 {
     //add local spaces and pages
     if (unpublishedWiki != null)
     {
         //add unexistent spaces from old structure
         //and update existing spaces with unpublished pages
         foreach (Space sp in unpublishedWiki.spaces)
         {
             if (actualWiki.ContainsSpace(sp.name))
             {
                 //The old local space containing local unpublished documents.
                 Space existingSpace = actualWiki[sp.name];
                 foreach (XWikiDocument xwd in sp.documents)
                 {
                     existingSpace.documents.Add(xwd);
                 }
                 existingSpace.published = true;
             }
             else
             {
                 sp.published = false;
                 actualWiki.spaces.Add(sp);
             }
         }
     }
 }