code: public void cancelEventDelivery(Object event) {
          PostingThreadState postingState = currentPostingThreadState.get();
          if (!postingState.isPosting) {
              throw new EventBusException(
                      "This method may only be called from inside event handling methods on the posting thread");
          } else if (event == null) {
              throw new EventBusException("Event may not be null");
          } else if (postingState.event != event) {
              throw new EventBusException("Only the currently handled event may be aborted");
          } else if (postingState.subscription.subscriberMethod.threadMode != ThreadMode.POSTING) {
              throw new EventBusException(" event handlers may only abort the incoming event");
          }
  
          postingState.canceled = true;
      }
docs: Called from a subscriber's event handling method, further event delivery will be canceled. Subsequent
  subscribers
  won't receive the event. Events are usually canceled by higher priority subscribers (see
  {@link Subscribe#priority()}). Canceling is restricted to event handling methods running in posting thread
  {@link ThreadMode#POSTING}.