title: Composite component with ReactiveFormsModule - ExpressionChangedAfterItHasBeenCheckedError
body: <p>I'm trying to create a composite component (a component that contains other "input" components). However, I can't make it work due to <code>ExpressionChangedAfterItHasBeenCheckedError</code> issue, that is thrown when a component is being initialized. Here's a demo of the issue that I managed to reproduce:</p>
  
  <p><a href="https://stackblitz.com/edit/angular-hvsqye" rel="nofollow noreferrer">https://stackblitz.com/edit/angular-hvsqye</a></p>
  
  <p>Any ideas what is going on? It starts to work when I replace <code>required</code> component with simple <code>input</code> inside <code>composite</code>, so I guess this has something to do with how they communicate.</p>
  
  <p>Thanks</p>