private void findNewFiles(
      File directory, Set<File> existing, boolean recurse, List<File> result) {
    File[] files = directory.listFiles();
    if (files != null) {
      for (File file : files) {
        if (file.isDirectory() && recurse) {
          findNewFiles(file, existing, true, result);
        } else if (!existing.contains(file)) {
          result.add(file);
        }
      }
    }
  }
Test the iterator returned is ok and deletion through the iterator is ok too. This is the
required functionality that eviction needs.

@throws Exception
imagepipeline-base/src/test/java/com/facebook/cache/disk/DefaultDiskStorageTest.java