onDeleted property Null safety
Called when the user taps the deleteIcon to delete the chip.
If null, the delete button will not appear on the chip.
The chip will not automatically remove itself: this just tells the app that the user tapped the delete button. In order to delete the chip, you have to do something similar to the following sample:
flutter create --sample=chip.DeletableChipAttributes.onDeleted.1 mysample
@override final VoidCallback? onDeleted;