For example Senior officers at Colditz often received parcels from home with stuff like cigars, chocolates, and spirits, sometimes through diplomatic agreements with the Red Cross. This was at a time when Germany in general was starving. They also organised theatre productions, orchestras, and even sports events.
I think this is just a relic of a different era and a different code of war - similar to how long before this Naval captains from opposing sides often shared meals after a ship's surrender. It is hard to imagine now.