#vulnerable code 
                                public static void postEvent(ApplicationType applicationType, ActionType actionType, ProtocolType protocolType, ProtocolMessage message) {
        if (message.getException() == null) {
            return;
        }

        ProtocolEvent protocolEvent = new ProtocolEvent(applicationType, actionType, protocolType, message);

        if (eventNotification) {
            EventControllerFactory.getSingletonController(EventControllerType.ASYNC).post(protocolEvent);
        }
    } 
                            #location 9 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public static void postEvent(ApplicationType applicationType, ActionType actionType, ProtocolType protocolType, ProtocolMessage message) {
        if (message.getException() == null) {
            return;
        }

        ProtocolEvent protocolEvent = new ProtocolEvent(applicationType, actionType, protocolType, message);

        if (eventNotification) {
            EventControllerFactory.getAsyncController().post(protocolEvent);
        }
    }