static @NotNull VcsRevisionNumber getHead(@NotNull GitRepository repository) {
    // we force update the GitRepository, because update is asynchronous, and thus the GitChangeProvider may be asked for changes
    // before the GitRepositoryUpdater has captures the current revision change and has updated the GitRepository.
    repository.update();
    final String rev = repository.getCurrentRevision();
    return rev != null ? new GitRevisionNumber(rev) : VcsRevisionNumber.NULL;
  }
static @NotNull VcsRevisionNumber getHead(@NotNull GitRepository repository)