title: When will @Predestroy be invoked on prototype-scoped beans?
body: <p>I would like to know when will the ApplicationContext call the method annotated with @PreDestroy on a prototype-scoped bean?</p>
  
  <p>a) Each time a bean instance become unreachable (eg. ready for GC)
  b) When the ApplicationContext is shutting down (eg. calling close(), stop(), destroy())</p>