code: private void validate(File root, Collection<URI> dirs) throws IOException {
      if (dirs == null)
        return;
      for (URI dir : dirs) {
        if (new File(dir.getPath()).getAbsolutePath().equals(
            root.getAbsolutePath())) {
          // we found the corresponding entry
          return;
        }
      }
      throwIOException("Error. Storage directory: " + root
          + " is not in the configured list of storage directories: " + dirs);
    }
docs: For sanity checking that the given storage directory was configured.