Takata.
Concerning AS 804, beside using optical detectors (see Airbus statement), I would add that the smoke warning(s) were triggered several hours after take off. At this point, such warnings would be very unlikely resulting from prior ground contamination of smoke detectors, which is what happen in most cases.
Who needs ground contamination? Because I would not let them smoke in the flightdeck, my first officers used to smoke in the forward toilet. I won't say how they overcame the detector (mostly). Its like pushing water uphill sometimes.