title: How to use a ViewPager with CollapsingToolbar without using NestedScrollView?
body: <p>I want to make several fragments in the main activity each having a RecyclerView such that I can swipe between them. Also in this activity, I have a collapsing toolbar on top of all these things.</p>
  <ol>
  <li>I tried using the RecyclerView Directly inside the ViewPager but unfortunately the Toolbar didn't Collapse (I think it needs a NestedScrollView)</li>
  <li>I added NestedScrollView outside the ViewPager which gave me an Exception on adding new items to any of the RecyclerViews   <code>java.lang.IndexOutOfBoundsException</code> which I found to be a bug caused by calling <code>runOnUiThread()</code> but if I loaded data using UI thread it would be too slow</li>
  <li>I tried using NestedScrollViews inside each fragment (wrapping the RecyclerViews) but it gave the same exception</li>
  </ol>
  <p>Is there any way to collapse the toolbar without NestedScrollView?</p>