combinedOrderedStringId function
Generates an ordered ID from a list of unordered IDs, that can be used to identify the list of IDs.
For example, this can be used to combine user IDs into a single ID that represents the group of users.
Implementation
String combinedOrderedStringId(List<String> ids) {
final sorted = ids..sort((a, b) => a.compareTo(b));
final combined = sorted.join('_');
return combined;
}