"AVOID using library private types in public APIs" - lint warning, even in in cookbook exa-CodePudding

I noticed the style error warning

My understanding of OOP and its nomenclature is sketchy at best and I don't quite understand the warning, but my actual question is, are the examples with this warning wrong, or sub-ideal - or does that style issue only apply in certain contexts that is perhaps not relevant to the examples and or I should ignore it, or is it an result of flutter/dart versions or some such or other?

CodePudding user response：

From the latest docs:

Subclasses should override this method to return a newly created
instance of their associated [State] subclass:

@override
State<MyWidget> createState() => _MyWidgetState();

So you should replace

@override
_AnimatedContainerAppState createState() => _AnimatedContainerAppState();

with

@override
State<AnimatedContainerApp> createState() => _AnimatedContainerAppState();