equals method Null safety
override
Compare two elements for being equal.
This should be a proper equality relation.
Implementation
@override
bool equals(Iterable<E>? elements1, Iterable<E>? elements2) {
if (identical(elements1, elements2)) return true;
if (elements1 == null || elements2 == null) return false;
var it1 = elements1.iterator;
var it2 = elements2.iterator;
while (true) {
var hasNext = it1.moveNext();
if (hasNext != it2.moveNext()) return false;
if (!hasNext) return true;
if (!_elementEquality.equals(it1.current, it2.current)) return false;
}
}