title: how to use assertj extracting map property
body: <p>I am using <code>AssertJ</code>. I have a class like <code>MyObj</code>. And I have a <code>List</code> of <code>MyObj</code>.</p>
  <pre class="lang-java prettyprint-override"><code>class MyObj {
      ...
      Map&lt;K,V&gt; myMap;
      ...
  }
  </code></pre>
  <p>When I use:</p>
  <ol>
  <li><code>assertThat(list).extracting(&quot;myMap&quot;)</code>, I cannot use <code>.containsKey()</code> method.</li>
  <li>I also tried using <code>assertThat(list).extracting(&quot;myMap&quot;, Map.class)</code>, but it does not work either.</li>
  </ol>
  <p>What is the right way of using it?</p>