children method
Returns already-materialised children only — an un-read Lazy<DI> is
skipped so iterating children() from _maybeFinish cannot
force-construct unrelated children. Snapshotted to survive re-entrant
register/unregister.
Implementation
Option<Iterable<DI>> children() {
return childrenContainer.map(
(e) => e.registry.unsortedDependencies
.toList(growable: false)
.map(_childFromDep)
.nonNulls,
);
}