title: how to convert HashMultiset<String> to Map<String,Integer>
body: <p>Is there some trick to convert <code>HashMultiset&lt;String&gt;</code> to <code>Map&lt;String,Integer&gt;</code>, except from iterating all the entries in the <code>Set</code>?<br>
  Update: The Integer should represent the count of String in the multiset.</p>