@Override
    public K next() {
      Node<K> p;
      if ((p = next) == null) {
        throw new NoSuchElementException();
      }
      K k = p.key;
      lastReturned = p;
      advance();
      return k;
    }
Base of key, value, and entry Iterators. Adds fields to Traverser to support iterator.remove.
geode-core/src/main/java/org/apache/geode/internal/concurrent/CompactConcurrentHashSet2.java