addAllIf method
Implementation
void addAllIf(/* bool | Condition */ condition, Iterable<E> elements) {
if (condition is Condition) condition = condition();
if (condition is bool && condition) addAll(elements);
}
void addAllIf(/* bool | Condition */ condition, Iterable<E> elements) {
if (condition is Condition) condition = condition();
if (condition is bool && condition) addAll(elements);
}