Most likely office space. Thee's a big customer support hub in Ireland. If you've ever spoken to Apple on the phone from the UK for example, it's almost always going to be to someone based in their Cork offices.
That I know, that's why I asked if the factory specifically is still operational.
They definitely do hardware R&D there [including on major recent launches] and a lot of product assembly. They also advertise production-line automation software gigs periodically for the plant in Little Island (the lesser-known site on the east side of the city which is neither of the offices everyone here knows about).
I think they have a big data center too but it's not like they have given me a tour there!