Status: IN
PreorderIterator's stack-of-iterators implementation — where each Composite node produces its own iterator via CreateIterator() factory method — concretely validates Factory Method's role as enabling infrastructure for recursive traversal: polymorphic iterator creation via factory methods is not just a convenience but a structural necessity for traversing heterogeneous composite trees where each node type may require different iteration behavior.
PreorderIterator's stack-of-factory-created-iterators concretely demonstrates Factory Method as recursive traversal infrastructure
Depends on (SL): preorder-iterator-stack-of-iterators, iterator-factory-method-creates-appropriate-iterator, recursive-structure-complete-infrastructure