NPE in ASYM_ENCRYPT

2019-05-09 08:38:39,518 ERROR [org.jgroups.protocols.UDP] (jgroups-10,Clusterd6c8baf6-b087-4deb-a0b2-dbab8302a80atrunk-83693,umstest-win10-3-24714) failed processing batch: java.lang.NullPointerException
    at org.jgroups.protocols.Encrypt.up(Encrypt.java:192)
    at org.jgroups.protocols.ASYM_ENCRYPT.up(ASYM_ENCRYPT.java:176)
    at org.jgroups.protocols.BARRIER.up(BARRIER.java:196)
    at org.groups.stack.Protocol.up(Protocol.java:371)
    at org.jgroups.protocols.FD_ALL.up(FD_ALL.java:216)
    at org.jgroups.stack.Protocol.up(Protocol.java:371)
    at org.jgroups.stack.Protocol.up(Protocol.java:371)
    at org.jgroups.stack.Protocol.up(Protocol.java:371)
    at org.jgroups.protocols.TP.passBatchUp(TP.java:1276)
    at org.jgroups.util.MaxOneThreadPerSender$BatchHandlerLoop.passBatchUp(MaxOneThreadPerSender.java:284)
    at org.jgroups.util.SubmitToThreadPool$BatchHandler.run(SubmitToThreadPool.java:136)
    at org.jgroups.util.MaxOneThreadPerSender$BatchHandlerLoop.run(MaxOneThreadPerSender.java:273)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at java.base/java.lang.Thread.run(Thread.java:834)