addItem method
Implementation
void addItem(T item, [bool prepend = true]) {
final key = itemKey(item);
_itemsMap[key] = item;
if (!isServerSide) {
if (prepend) {
_localPaginationItems.insert(0, item);
} else {
_localPaginationItems.add(item);
}
}
updateState(
who: 'addItem',
displayItems: value.displayItems.copyWithItem(itemFactory(item), prepend),
totalItems: value.totalItems + 1,
);
}