Is Article 49 of the Charter of Fundamental Rights to be interpreted as precluding a situation in which a person is convicted on the ground that he obtained export refunds, to which he was not entitled, by means of deceitful practices or the making of false declarations as to the nature of the goods in respect of which the refunds were requested, although, as a result of changes in the rules which occurred subsequent to the facts of the case, the goods that were in fact exported by that person have since become eligible for those refunds?