code: public synchronized String[] getExcludedDirectories() {
          slowScan();
          String[] directories = new String[dirsExcluded.size()];
          dirsExcluded.copyInto(directories);
          return directories;
      }
docs: Return the names of the directories which matched at least one of the
  include patterns and at least one of the exclude patterns.
  The names are relative to the base directory. This involves
  performing a slow scan if one has not already been completed.
  
  @return the names of the directories which matched at least one of the
  include patterns and at least one of the exclude patterns.
  
  @see #slowScan