How to breed villagers in Minecraft 1.12.2?

I’m currently playing a survival world with my friends, and we are living in a village, which only has 3 villagers left.

I’ve tried breeding them by enclosing multiple doors under the village, trading with the villagers, and giving them crops, but they just ignore each other.

Has anything changed since I last played (Minecraft 1.10)?

I checked the wiki but only found info for Minecraft 1.14.

Any help would be greatly appreciated.