code: public List<SystemEventListener> getListenersForEventClass(Class<? extends SystemEvent> facesEventClass) {
  
          if (null == listener) {
              List<SystemEventListener> list = new ArrayList<SystemEventListener>(1);
              list.add(context.getExceptionHandler());
              listener = Collections.unmodifiableList(list);
          }
          return listener;
  
      }
docs: <p class="changed_added_2_0">Return a <code>List</code> that
  contains a single entry, the {@link
  javax.faces.context.ExceptionHandler} for the current
  request.</p>