Baby zombie variants don't appear in debug world

The bug

The changelog says:

Entity types that can be babies will have a baby version included above the adult version

However, this only applies to ageable babies. Baby zombies, drowned, etc. that never age do not appear.

How to reproduce

1. Create a new debug world (hold alt while changing “world type”)

2. Find the zombie

3. Look above it

Expected results

Should be a baby zombie there

Observed results

There’s none