mapNotNull<E> method
Similar to map, but MAY return a non-nullable type.
int? f(String? e) => (e == null) ? 0 : e.length;
List<int?> list1 = ["xxx", "xx", null, "x"].map(f).toList();
expect(list1, isA<List<int?>>());
List<int?> list2 = ["xxx", "xx", null, "x"].mapNotNull(f).toList();
expect(list2, isA<List<int>>());
Implementation
Iterable<E> mapNotNull<E>(E? Function(T? e) f) => map(f).cast();