class Pair {

  @SuppressWarnings({"unchecked"})
  @Override
  public boolean equals(Object obj) {
    if (!(obj instanceof Pair)) {
      return false;
    }
    final Pair<Object, Object> other = (Pair<Object, Object>) obj;
    return Objects.equal(v1, other.v1) && Objects.equal(v2, other.v2);
  }

}