code: @SuppressWarnings("unchecked")
      public F.Tuple<AbstractDeadboltAction<?>, Http.RequestHeader> getDeferredAction(final Http.RequestHeader request)
      {
          return request.attrs().getOptional(ACTION_DEFERRED).map(action -> {
              action.delegate = this;
              return F.<AbstractDeadboltAction<?>, Http.RequestHeader>Tuple(action, request.removeAttr(ACTION_DEFERRED).addAttr(IGNORE_DEFERRED_FLAG, true));
          }).orElseGet(() -> F.Tuple(null, request));
      }
docs: Get the deferred action from the request.
  
  @param request the request
  @return a tuple containing the deferred action (or null if it doesn't exist) and the cleaned up request you should pass on