code: @SuppressWarnings("unchecked")
      public Collection<String> listFolders(File folder) {
          IOFileFilter ioFileFilter = FileFilterUtils.makeSVNAware(FileFilterUtils.makeCVSAware(FileFilterUtils.trueFileFilter()));
          Collection<File> files = FileUtils.listFiles(folder, FileFilterUtils.fileFileFilter(), ioFileFilter);
          Set<String> ret = newTreeSet();
          for (File file : files) {
              ret.add(file.getParentFile().getAbsolutePath());
          }
          return ret;
      }
docs: Recurse in the folder to get the list all files and folders of all non svn files
  
  @param folder the folder to parse