CopyOnWriteArrayList类set方法疑惑

Question

在CopyOnWriteArrayList类的set方法中有一段setArray(elements)代码，实际上这段代码并未对elements做任何改动，实现的volatile语意并不对CopyOnWriteArrayList实例产生任何影响，为什么还是要保留这行语句？ public E set(int index, E element) { final ReentrantLock lock = this.lock; lock.lock(); try { Object[] elements = getArray(); E oldValue = get(elements, index); if (oldValue != element) { int len = elements.length; Object[] newElements = Arrays.copyOf(elements, len); newElements[index] = element; setArray(newElements); } else {　　　　　　　// 就是这一段代码 setArray(elements); } return oldValue; } finally { lock.unlock(); } } private E get(Object[] a, int index) { return (E) a[index]; } final void setArray(Object[] a) { array = a; }