Put the summary of the bug you're having here
What I expected to happen was...:
Spawning Villagers should be a random villager
What actually happened was...:
Villager eggs spawn only Nitwits
Steps to Reproduce:
1. Spawn a villager with a spawn egg
2. ...
3. ...
Environment
Windows 10
I think this is designed. They made villagers acquire occupations based on what kinds of blocks they find in their neighborhood.