title: Sharing view models between activity and its fragment is not calling observable in the activity
body: <p>I am using view pager. I have created a shared view model for my activity and the fragments in my view pager. The problem is the observer in the activity doesn't get called when I set the MutableLiveData value in my view model. </p>
  
  <p>I using following lines to initialise my view models</p>
  
  <blockquote>
    <ol>
    <li><p>in activty: viewModel = ViewModelProviders.of(this).get(MyViewModel.class);</p></li>
    <li><p>in fragment: viewModel = ViewModelProviders.of(getActivity()).get(MyViewModel.class);</p></li>
    </ol>
  </blockquote>
  
  <p>While debugging I found that my observer of the activity gets removed on the fragment's onCreated.</p>
  
  <p>As far as I know both the fragment and the activity should have the same view model instance.</p>