isChildRegistered method
Children are registered as Lazy<DI> (see registerChild), so probe
for that exact key — isRegistered<DI> would not match under the
strict-keying contract.
Implementation
bool isChildRegistered({
Entity groupEntity = const DefaultEntity(),
}) {
final g = groupEntity.preferOverDefault(focusGroup);
return switch (childrenContainer) {
Some(value: final c) => c.isRegistered<Lazy<DI>>(groupEntity: g),
None() => false,
};
}