Lawsuit involving a controversy over the ownership of shares. Existence of concurrent arbitration proceedings concerning the exclusion and the determination of the assets owed to the shareholder holding the shares. Possibility of issuing an official communication to the arbitral tribunal reporting the existence of the court claim, provided it is strictly informative and neutral in nature. Impossibility for the state court to anticipate a ruling on the enforceability of the arbitration clause against a third party or to previously recognize the existence of external prejudicial matter: