title: When would Fragment's onDestroyView be called, but it wouldn't be destroyed?
body: <p>Looking at a Fragment's lifecycle, I am not sure about the scenarios that can happen here.
  There are 2 possible ways to go when a Fragment stops being active. </p>
  
  <ol>
  <li>call the appropriate callbacks, destroy view and then destroy the fragment</li>
  <li>call the callbacks, destroy view, but keep the fragment itself alive</li>
  </ol>
  
  <p>Which of the two alternatives is done in which situations? What decides which of them?
  If a fragment is added to the backstack, then removed/replaced, why not throw it away? Why keep it? </p>
  
  <p>Edit: it dawned on me, could it be dependant on whether the fragment is retained or not?</p>
  
  <p><img src="https://i.stack.imgur.com/BwEWN.png" alt="enter image description here"></p>