[2020] They Jump now!?

when did the zombies start jumping over gaps? (edit: what version update) And how far can they jump now?

Currently have a 2 wide gap all around my base with a wall inside that... Was noticing them on the wrong side of the moat and wasn't sure how they were getting across until I watched a basic zombie jump the gap today. So would a 3 or 4 wide gap be enough?

For the record I have all my loot and crafting in the base but I rarely spend time inside it... Most nights I spend mining. Then I spend a few minutes starting so crafting / forges then I leave before I get too much heat (activity).

Edit: u/stabbyinc a dev said 18.4 is when they gained the ability of jump up to 4 blocks... Thank you.