How do I make a modded building flippable?

[lupuchard]

I couldn't seem to find a property for this in the docs, or anything about flippability in the prototypes of flippable vanilla entities, but when I try to flip my modded building it says "X cannot be flipped" and I'd like the fluid inputs to be able to be flipped.

cannotbeflipped.png (439.56 KiB) Viewed 46 times

[Osmo]

https://lua-api.factorio.com/latest/pro ... d_symmetry