title: How to empty a Map<String List<String>>
body: <p>In my method I have a Map that contains a List for the mapped type</p>
  
  <pre><code>private static Map&lt;String, List&lt;String&gt;&gt; myMap;
  </code></pre>
  
  <p>It throws an <code>UnsupportedOperationException</code> when I try to use the <code>clear()</code> method of Map</p>
  
  <p>How do I empty it?</p>