How can a stateless widget contain a stateful widget if it is immutable?

Question

When a stateful widget's state changes it calls the build method and rebuilds its children. However if a stateful widget (eg TextControl()) is used inside a stateless widget (MyApp) what happens to the stateless widget when the stateful widget changes state? Does the stateless widget get recreated or does only the stateful widget change? code snip of TextControl inside MyApp

Answer 1

Seems like duplicate of this. Please elaborate if you're looking for different answer.