public @Nullable Iterator<ChangesBunch> getBackBunchedIterator(final AbstractVcs vcs, final VirtualFile root, final RepositoryLocation location, final int bunchSize) {
    final ChangesCacheFile cacheFile = myCachesHolder.getCacheFile(vcs, root, location);
    try {
      if (! cacheFile.isEmpty()) {
        return cacheFile.getBackBunchedIterator(bunchSize);
      }
    }
    catch (IOException e) {
      LOG.error(e);
    }
    return null;
  }
public @Nullable Iterator<ChangesBunch> getBackBunchedIterator(final AbstractVcs vcs, final VirtualFile root, final RepositoryLocation location, final int bunchSize)