getGrandchildString method
Returns the nested value at childKey → grandChildKey as a String,
or null if either key is missing or the value is not a String.
Audited: 2026-06-12 11:26 EDT
Implementation
@useResult
String? getGrandchildString(String childKey, String grandChildKey) {
final dynamic value = getGrandchild(childKey, grandChildKey);
return value is String ? value : null;
}