title: prefer const literals as parameters of constructors on @immutable classes in android studio
body: <p>In the following code, I'm getting inspection warning with 'prefer const literals as parameters of constructors on @immutable classes' and it's annoying. What should I do to make it go away?</p>
  <p><a href="https://i.stack.imgur.com/efMeP.png" rel="noreferrer">screenshot from ide</a></p>
  <pre class="lang-dart prettyprint-override"><code>Container(
          margin: const EdgeInsets.all(20),
          width: double.infinity,
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              TextField(
                decoration: InputDecoration(
                    border: OutlineInputBorder(),
                    hintText: 'Enter a search term'),
              ),
              Text(&quot;these are the search results&quot;, textAlign: TextAlign.left),
            ],
          ),
        )
  </code></pre>
  <p>I have tried to make every constructor call 'const' with no avail.</p>
  <pre><code>Container(
          margin: const EdgeInsets.all(20),
          width: double.infinity,
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              const TextField(
                decoration: const InputDecoration(
                    border: const OutlineInputBorder(),
                    hintText: 'Enter a search term'),
              ),
              const Text(&quot;these are the search results&quot;, textAlign: TextAlign.left),
            ],
          ),
        ),
  </code></pre>