customSemanticsActions property Null safety
A map from each supported
CustomSemanticsAction to a provided handler.
The handler associated with each custom action is called whenever a semantics action of type SemanticsAction.customAction is received. The provided argument will be an identifier used to retrieve an instance of a custom action which can then retrieve the correct handler from this map.
CustomSemanticsAction, for an explanation of custom actions.
final Map<CustomSemanticsAction, VoidCallback>? customSemanticsActions;