title: How the iterator is failsafe in concurrent hash map
body: <p>As I know that iterator in the <code>CopyOnWriteArrayList</code> is <em>thread-safe</em> due to snapshot reference to the  copy of <code>arrayList</code> at the time of iterator is created, and in this all mutative operations <code>(add, set, and so on)</code> are implemented by making a <em>fresh copy of the underlying array</em> so they do not  affect the copy referred by snapshot reference and same for <code>CopyOnWriteArraySet</code>, </p>
  
  <p>But struggling in case of <code>ConcurrentHashMap</code>, so please share your views how the iterator is fail-safe in case of <code>ConcurrentHaspMap</code></p>