java.lang.NullPointerException
	at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1690)
	at org.jgroups.util.MaxOneThreadPerSender$MessageTable.get(MaxOneThreadPerSender.java:84)
	at org.jgroups.util.MaxOneThreadPerSender$MessageTable.process(MaxOneThreadPerSender.java:91)
	at org.jgroups.util.MaxOneThreadPerSender.loopback(MaxOneThreadPerSender.java:54)
	at org.jgroups.protocols.TP.loopback(TP.java:1104)
	at org.jgroups.protocols.TP.down(TP.java:1029)
	at org.jgroups.protocols.RED.down(RED.java:115)
	at org.jgroups.stack.Protocol.down(Protocol.java:292)
	at org.jgroups.stack.Protocol.down(Protocol.java:292)
	at org.jgroups.protocols.FD_SOCK2.broadcastSuspectMessage(FD_SOCK2.java:511)
	at org.jgroups.protocols.FD_SOCK2.connectToNextPingDest(FD_SOCK2.java:384)
	at org.jgroups.protocols.FD_SOCK2.handle(FD_SOCK2.java:342)
	at org.jgroups.protocols.FD_SOCK2.handle(FD_SOCK2.java:31)
	at org.jgroups.util.ProcessingQueue.process(ProcessingQueue.java:55)
	at org.jgroups.util.ProcessingQueue.add(ProcessingQueue.java:35)
	at org.jgroups.protocols.FD_SOCK2.connectionClosed(FD_SOCK2.java:284)
	at org.jgroups.blocks.cs.BaseServer.notifyConnectionClosed(BaseServer.java:458)
	at org.jgroups.blocks.cs.BaseServer.closeConnection(BaseServer.java:361)
	at org.jgroups.blocks.cs.BaseServer.closeConnection(BaseServer.java:355)
	at org.jgroups.blocks.cs.NioConnection$Reader._run(NioConnection.java:506)
	at org.jgroups.blocks.cs.NioConnection$Reader.run(NioConnection.java:483)
	at java.base/java.lang.Thread.run(Thread.java:829)