thenBy method
Combines this Comparator and the given selector such that the latter is applied only when the former considered values equal.
myList.sort(compareBy((o) => o.firstProperty).thenBy((o) => o.secondProperty))
Implementation
Comparator<T> thenBy(Comparable Function(T) selector) {
final thenComparator = compareBy(selector);
return then(thenComparator);
}