docs: public void checkValues(CmsObject cms) throws CmsException {
  
          if (isEnabled() && (m_destinationPathInRfs == null)) {
              // if enabled, it's required to have RFS destination folder available
              throw new CmsSynchronizeException(Messages.get().container(Messages.ERR_NO_RFS_DESTINATION_0));
          }
          if (isEnabled() && ((m_sourceListInVfs == null) || (m_sourceListInVfs.size() == 0))) {
              // if enabled, it's required to have at last one source folder
              throw new CmsSynchronizeException(Messages.get().container(Messages.ERR_NO_VFS_SOURCE_0));
          }
          Iterator<String> i = m_sourceListInVfs.iterator();
          // store the current site root
          String currentSite = cms.getRequestContext().getSiteRoot();
          // switch to root site
          cms.getRequestContext().setSiteRoot("");
          try {
              while (i.hasNext()) {
                  // try to read all given resources, this will cause an error if the resource does not exist
                  cms.readResource(i.next());
              }
          } finally {
              // reset to current site root
              cms.getRequestContext().setSiteRoot(currentSite);
          }
      }