code: public synchronized String[] getNotIncludedDirectories() {
          slowScan();
          String[] directories = new String[dirsNotIncluded.size()];
          dirsNotIncluded.copyInto(directories);
          return directories;
      }
docs: Return the names of the directories which matched none of the include
  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 none of the include
  patterns.
  
  @see #slowScan