final Entry<K, V> nextEntry() {
            if (modCount != expectedModCount)
                throw new ConcurrentModificationException();
            Entry<K, V> e = next;
            if (e == null)
                throw new NoSuchElementException();

            if ((next = e.next) == null) {
                Entry[] t = table;
                while (index < t.length && (next = t[index++]) == null)
                    ;
            }
            current = e;
            return e;
        }
Like addEntry except that this version is used when creating entries as
part of Map construction or "pseudo-construction" (cloning,
deserialization). This version needn't worry about resizing the table.

Subclass overrides this to alter the behavior of SafelyHashMap(Map),
clone, and readObject.
src/main/java/com/alibaba/fastjson/util/AntiCollisionHashMap.java