onChange method Null safety
- @protected
 - @mustCallSuper
 
- Change<
ConnectivityState> change 
@mustCallSuper, @protected, inherited
    Called whenever a change occurs with the given change.
A change occurs when a new state is emitted.
onChange is called before the state of the cubit is updated.
onChange is a great spot to add logging/analytics for a specific cubit.
Note: super.onChange should always be called first.
@override
void onChange(Change change) {
  // Always call super.onChange with the current change
  super.onChange(change);
  // Custom onChange logic goes here
}
See also:
BlocObserverfor observingCubitbehavior globally.
Implementation
@protected
@mustCallSuper
void onChange(Change<State> change) {
  // ignore: invalid_use_of_protected_member
  _blocObserver?.onChange(this, change);
}