1. override
void notifyClients(InheritedWidget oldWidget)

Notify other objects that the wiget associated with this element has changed.

Called during update after changing the widget associated with this element but before rebuilding this element.

Source 

@override
void notifyClients(InheritedWidget oldWidget) {
  if (!widget.updateShouldNotify(oldWidget))
    return;
  dispatchDependenciesChanged();
}