2019-05-03 16:58:54.468 [pool-1-thread-5]  EventBusImplementation.lambda$doFireThreadPerHandler$1()  WARNING: Exception during execution of event: tigase.pubsub.modules.PresenceCollectorModule.PresenceChangeEvent
java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
        at tigase.eventbus.impl.ReflectEventListenerHandler.dispatch(ReflectEventListenerHandler.java:48)
        at tigase.eventbus.impl.EventBusImplementation.lambda$doFireThreadPerHandler$1(EventBusImplementation.java:306)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.reflect.InvocationTargetException
        at sun.reflect.GeneratedMethodAccessor38.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at tigase.eventbus.impl.ReflectEventListenerHandler.dispatch(ReflectEventListenerHandler.java:46)
        at tigase.eventbus.impl.EventBusImplementation.lambda$doFireThreadPerHandler$1(EventBusImplementation.java:306)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException: Element child can not be null.
        at tigase.xml.Element.addChild(Element.java:161)
        at tigase.pubsub.modules.PublishItemModule.publishLastItem(PublishItemModule.java:403)
        at tigase.pubsub.modules.PublishItemModule.onPresenceChangeEvent(PublishItemModule.java:710)
        at sun.reflect.GeneratedMethodAccessor38.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at tigase.eventbus.impl.ReflectEventListenerHandler.dispatch(ReflectEventListenerHandler.java:46)
        at tigase.eventbus.impl.EventBusImplementation.lambda$doFireThreadPerHandler$1(EventBusImplementation.java:306)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)