title: Is that Flutter need required and late for null safety in sdk version up to 2.7.0?
body: <p>In the below code, this code occurs error that <code>late</code> and <code>required</code> are not available in the flutter version 2.7.0.</p>
  <pre class="lang-dart prettyprint-override"><code>  late CameraController _controller;
    late Future&lt;void&gt; _initializeControllerFuture;  
  
  ...
  
    const DisplayPictureScreen({Key? key, required this.imagePath})
        : super(key: key);
  </code></pre>
  <p>So, I change the flutter version up to 2.1.2 like this, and solved this problem right away.</p>
  <pre class="lang-dart prettyprint-override"><code>environment:
    sdk: &quot;&gt;=2.12.0 &lt;3.0.0&quot;
  </code></pre>
  <p>Is that Flutter need other definition instead of <code>required</code> and <code>late</code> for null safety in sdk version up to 2.7.0?</p>
  <p>If yes, how I changes definition <code>required</code> and <code>late</code> in sdk version up to 2.7.0?</p>