Sending Object + Message via websocket when database is modified

Question

I'm using hibernate and JpaRepository + PostgreSQL. I have the following code which listens to any modifications made to the database.

public class PermitEntityListener {

    @PrePersist
    public void prePersist(Permit target) {
        perform(target, INSERTED);
    }

    @PreUpdate
    public void preUpdate(Permit target) {
        perform(target, UPDATED);
    }

    @PreRemove
    public void preRemove(Permit target) {
        perform(target, DELETED);
    }

    @Transactional(MANDATORY)
    private void perform(Permit target, Action action) {
        EntityManager entityManager = BeanUtil.getBean(EntityManager.class);
        entityManager.persist(new PermitHistory(target, action));
        //Send permitHistory to client via websocket to update changes
        PermitUpdates updates = new PermitUpdates();
        updates.sendUpdatedPermit(new PermitHistory(target, action));
    }
}

In the method perform, it is where changes made would be updated into a new table. At this point, i wish to also send this "PermitHistory" back to the user via a web socket. This is so that when the user is modifying/viewing the table, on the client side he will be able to receive a prompt that new changes have been made to the fields so he can choose to refresh to display the updates.

Edit: I created a new class "PermitUpdates"

public class PermitUpdates {

    @Autowired
    private SimpMessagingTemplate template;

    public void sendUpdatedPermit(PermitHistory permitHistory) {
        if (permitHistory != null) {
            this.template.convertAndSend("/changes", permitHistory);
        }
    }
}

I also added a WebSocketConfig class

@Configuration
@EnableWebSocketMessageBroker
public class WebSocketConfig implements WebSocketMessageBrokerConfigurer {

    @Override
    public void configureMessageBroker(MessageBrokerRegistry config) {
        config.enableSimpleBroker("/changes");
        config.setApplicationDestinationPrefixes("/app");
    }

    @Override
    public void registerStompEndpoints(StompEndpointRegistry registry) {
        registry.addEndpoint("/gs-guide-websocket").withSockJS();
    }

}

With this a new error occured:

Caused by: java.lang.NullPointerException
    at com.example.historical.websoc.PermitUpdates.sendUpdatedPermit(PermitUpdates.java:19)

What am i doing wrong?