onDefer property
A Future which resolves only if an action has not been cancelled, and
and before the action execution. Use this future to begin a chain for
#defer. Beginning a chain with this future allows for lazy evaluation
of the deferring future.
This future resolves to false if the action has been cancelled. If the
action is cancelled, no futures registered with defer will be awaited
before resolving the onDone future.
Implementation
Future<bool> get onDefer => _onDefer;