code: public synchronized String[] getDeselectedDirectories() {
          slowScan();
          String[] directories = new String[dirsDeselected.size()];
          dirsDeselected.copyInto(directories);
          return directories;
      }
docs: <p>Return the names of the directories which were selected out and
  therefore not ultimately included.</p>
  
  <p>The names are relative to the base directory. This involves
  performing a slow scan if one has not already been completed.</p>
  
  @return the names of the directories which were deselected.
  
  @see #slowScan