title: What does Class<? extends ParentClass> mean?
body: <p>I found a method like the one below. </p>
  
  <pre><code>public void simpleTest(Class &lt;? extends ParentClass&gt; myClass){
  
  }
  </code></pre>
  
  <p>I didn't understand the expression : <code>Class &lt;? extends ParentClass&gt; myClass</code> here.</p>
  
  <p>Can anyone explain it?</p>