05:52:55,313 ERROR [org.jgroups.util.TimeScheduler3] (thread-6,null,xa-load-2) JGRP000169: failed executing task MERGE3: InfoSender: java.lang.NullPointerException
at org.jgroups.protocols.kubernetes.KUBE_PING.readAll(KUBE_PING.java:313)
at org.jgroups.protocols.kubernetes.KUBE_PING.findMembers(KUBE_PING.java:206)
at org.jgroups.protocols.Discovery.invokeFindMembers(Discovery.java:216)
at org.jgroups.protocols.Discovery.findMembers(Discovery.java:241)
at org.jgroups.protocols.Discovery.down(Discovery.java:384)
at org.jgroups.protocols.MERGE3$InfoSender.run(MERGE3.java:413)
at org.jgroups.util.TimeScheduler3$Task.run(TimeScheduler3.java:328)
at org.jgroups.util.TimeScheduler3$RecurringTask.run(TimeScheduler3.java:362)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.jboss.as.clustering.jgroups.ClassLoaderThreadFactory.lambda$newThread$0(ClassLoaderThreadFactory.java:52)
at java.lang.Thread.run(Thread.java:748)

https://github.com/jgroups-extras/jgroups-kubernetes/issues/39
https://github.com/jgroups-extras/jgroups-kubernetes/pull/88

Will be resolved with a next jgroups-kubernetes upgrade.