Are Article 2(1) and 2(2)(a) and Article 6(1) of Council Directive 2000/78/EC of 27 November 2000 establishing a general framework for equal treatment in employment and occupation and the principles of legal certainty, maintenance of established rights and effectiveness of EU law to be interpreted as precluding national legislation – such as that at issue in the main proceedings – under which a previously advantaged category of civil servants is retroactively no longer entitled to pension benefits accruing on the basis of a pension adjustment, and which, in that way (retroactive removal of the previously advantaged category by now placing it on an equal footing with the previously disadvantaged category), has the effect that the previously disadvantaged category of civil servants is also not/no longer entitled to pension benefits accruing on the basis of the pension adjustment to which the latter category would have been entitled because of discrimination on grounds of age which has already been (on several occasions) judicially established – as a result of the non-application of a national provision which is contrary to EU law for the purpose of establishing equal treatment with the previously advantaged category?