@NotNull
  public static GraphCommit<Integer> createIntCommit(int id, @NotNull List<Integer> parents, long timestamp) {
    if (parents.size() == 1) {
      return new IntGraphCommit.SingleParent(timestamp, id, parents.get(0));
    }
    return new IntGraphCommit.MultiParent(timestamp, id, Ints.toArray(parents));
  }
@NotNull
  public static GraphCommit<Integer> createIntCommit(int id, @NotNull List<Integer> parents, long timestamp)