code: public synchronized String[] getExcludedFiles() {
          slowScan();
          String[] files = new String[filesExcluded.size()];
          filesExcluded.copyInto(files);
          return files;
      }
docs: Return the names of the files 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 files which matched at least one of the
  include patterns and at least one of the exclude patterns.
  
  @see #slowScan