inputs are not considered in form validation when using ng-content
<p>Given the following component (with selector my-template):</p>

<pre><code>&lt;form #theForm="ngForm"&gt;
    &lt;ng-content&gt;&lt;/ng-content&gt;
&lt;/form&gt;
</code></pre>

<p>and use it like this:</p>

<pre><code>&lt;my-template&gt;
    &lt;input type="text" required name="firstName" [(ngModel)]="firstName"/&gt;
&lt;/my-template&gt;
</code></pre>

<p>The form is always valid - even though the input is invalid. How can I make this work so that the form is invalid when the input is invalid?</p>

<p>Live demo:
<a href="https://plnkr.co/edit/lWUe6oeBk6ccsE2JxNKb?p=preview" rel="noreferrer">https://plnkr.co/edit/lWUe6oeBk6ccsE2JxNKb?p=preview</a></p>