Action to annul an arbitral award. Failure to comply with the arbitrator's duty of disclosure (Article 14, § 1º, of the Brazilian Arbitration Act). Arbitrator and counsel for one of the parties who served on the same arbitral tribunal in a prior case. Counsel who had acted as president of the arbitral tribunal, upon nomination by the arbitrator. Nullity of the arbitral award, as well as of all other acts performed in the arbitration proceedings (Article 32, VIII, of the Brazilian Arbitration Act):