Action to annul an arbitration award. Failure to comply with the arbitrator's duty of disclosure (Article 14, § 1º, of the Brazilian Arbitration Act). President of the arbitral tribunal who did not promptly and timely disclose his appointment by one of the parties to serve on the arbitral tribunal in another dispute involving a similar legal relationship. Nullity of the arbitration award, as well as of all other acts performed in the arbitration proceedings (Article 32, VIII, of the Brazilian Arbitration Act):