code: public void logErrorChanges(ErrorLog errorLog, Set<String> removed, Set<String> added) throws IOException
     {
        // backup the remove and add iterators
        if(errorLog != null)
        {
           errorLog.writeChanges(removed, added);
        }
     }
docs: Log unindexed changes into error.log
  
  @param removed
  set of removed node uuids
  @param added
  map of added node states and uuids
  @throws IOException