NikicClassLikeNameTrait

Renders a class-like reference (parent class, implemented interface, parent interface) while preserving whether the source wrote it fully qualified.

Name::toString() drops the leading separator, so extends \Countable and extends Countable both come through as "Countable". Downstream, TypeNameResolver then treats the qualified form as namespace-relative and produces ids such as \Dom\Countable. Those ids are wrong, and while ClassHierarchyResolver currently repairs them through its short-name fallback, the repair picks the global interface — which is the same failure mode that made MongoDB\BSON\Persistable resolve its Serializable parent to the global \Serializable (see the interface serializer).

Keeping the leading separator lets TypeNameResolver short-circuit on "already fully qualified" and yields the id the source actually meant.