createChildBackButtonDispatcher method Null safety

ChildBackButtonDispatcher createChildBackButtonDispatcher()

Creates a ChildBackButtonDispatcher that is a direct descendant of this back button dispatcher.

To participate in handling the pop route request, call the takePriority on the ChildBackButtonDispatcher created from this method.

When the pop route request is handled by this back button dispatcher, it propagate the request to its direct descendants that have called the takePriority method. If there are multiple candidates, the latest one that called the takePriority wins the right to handle the request. If the latest one does not handle the request (by returning a future of false in ChildBackButtonDispatcher.notifiedByParent), the second latest one will then have the right to handle the request. This dispatcher continues finding the next candidate until there are no more candidates and finally handles the request itself.


ChildBackButtonDispatcher createChildBackButtonDispatcher() {
  return ChildBackButtonDispatcher(this);