title: Merge lists with stream API
body: <p>I have the following situation</p>
  <pre><code>Map&lt;Key, ListContainer&gt; map; 
  
  public class ListContainer {
    List&lt;AClass&gt; lst;
  }
  </code></pre>
  <p>I have to merge all the lists <code>lst</code> from the <code>ListContainer</code> objects from a <code>Map</code> map.</p>
  <pre><code>public static void main(String[] args) {
     List&lt;AClass&gt; alltheObjectsAClass = map.values().stream(). // continue....    
  }
  </code></pre>
  <p>Any idea how, using Java 8 stream API?</p>