onRefresh property
Refresh callback.
Triggered on refresh.
When null, disable refresh.
The Header current state is IndicatorMode.processing.
More see IndicatorNotifier._onTask.
The return value can be IndicatorResult,
the default processing result is IndicatorResult.success,
and IndicatorResult.fail when an exception occurs.
When EasyRefreshController.controlFinishRefresh is true,
the return value is invalid.
Implementation
final FutureOr Function()? onRefresh;