title: clearing selection is not working in select2
body: <p>I have implemented select2 widget, version 4. It works, but the x icon. It is not clearing the selection.</p>
  
  <p>If you see this doc: <a href="https://select2.github.io/options.html">https://select2.github.io/options.html</a>, it says that this a problem in fact, but the documentation is incomplete for this.</p>
  
  <p>Anyone has solved this already?</p>
  
  <p>Thanks
  Jaime</p>