NextPageKeyCallback<PageKeyType, ItemType> typedef
NextPageKeyCallback<PageKeyType, ItemType> =
PageKeyType? Function(PagingState<PageKeyType, ItemType> state)
A callback to get the next page key.
If this function returns null, it indicates that there are no more pages to load.
Implementation
typedef NextPageKeyCallback<PageKeyType, ItemType> = PageKeyType? Function(
PagingState<PageKeyType, ItemType> state);