public static void saveAuthStore() {
    FileOutputStream out = null;
    try {
      if (!CONFIG_DIRECTORY.exists()) {
        CONFIG_DIRECTORY.mkdirs();
      }
      out = new FileOutputStream(USER_AUTH_FILE_BAK);
      authStoreUtils.save(persistentAuthStore, out);
      out.close();
      FileUtils.copyFile(USER_AUTH_FILE_BAK, USER_AUTH_FILE);
      FileUtils.deleteQuietly(USER_AUTH_FILE_BAK);
    } catch (IOException e) {
      LOGGER.error("Can't save auth store", e);
    } finally {
      IOUtils.closeQuietly(out);
    }

  }
Returns whether a folder contains a given file

@param folder A folder
@param file   A file
@return whether a folder contains a given file
olv-vfs/src/main/java/pl/otros/vfs/browser/util/VFSUtils.java