title: Flutter - RefreshIndicator on a child of CustomScrollView
body: <p>So, I have a <code>CustomScrollView</code> with a <code>SliverAppBar</code> and a <code>SliverList</code>. The <code>SliverList</code> has multiple non-sliver children widgets.</p>
  <pre class="lang-dart prettyprint-override"><code>CustomScrollView(
    slivers: [
      SliverAppBar(title: Text('some title')),
      SliverList(
        delegate: SliverChildListDelegate(
          [
            // non sliver children
          ],
        ),
      ),
    ],
  );
  </code></pre>
  <p>I want the content (non sliver children) of the <code>CustomScrollView</code> to have pull down to refresh. I don't want to put the <code>RefreshIndicator</code> on top of the scroll view because that will also reload the <code>SliverAppBar</code>.</p>
  <p>I tried wrapping all the non-sliver children with a Column and wrapping that Column in the RefreshIndicator but that didn't work.</p>
  <p>How do I do this? Thanks.</p>