title: Sort Guava Multimap by number of values
body: <p>If I have a Guava Multimap, how would I sort the entries based on the number of values for the given key?</p>
  
  <p>For instance:</p>
  
  <pre><code>Multimap&lt;String, String&gt; multiMap = ArrayListMultimap.create();
  multiMap.put("foo", "1");
  multiMap.put("bar", "2");
  multiMap.put("bar", "3");
  multiMap.put("bar", "99");
  </code></pre>
  
  <p>Given this, when iterating over multiMap, how would I get the "bar" entries to come first (since "bar" has 3 values vs. only 1 for "foo")?</p>