If the statistics for JGroups is enabled (default) there is a race condition if nodes are joining.
It could happen that the local cluster and XSite cluster (JChannel) connecting at the same time and access the same internal Map.

2022-05-16 04:42:14,822 ERROR (main) [org.jgroups.JChannel] JGRP000016: exception in channelConnected callback: java.util.ConcurrentModificationException java.util.ConcurrentModificationException
    at java.base/java.util.HashMap.computeIfAbsent(HashMap.java:1226)
    at org.infinispan.remoting.transport.jgroups.JGroupsTransport.channelConnected(JGroupsTransport.java:1515)
    at org.jgroups.JChannel.lambda$notifyChannelConnected$1(JChannel.java:1104)
    at java.base/java.util.concurrent.CopyOnWriteArrayList.forEach(CopyOnWriteArrayList.java:807)
    at java.base/java.util.concurrent.CopyOnWriteArraySet.forEach(CopyOnWriteArraySet.java:425)
    at org.jgroups.JChannel.notifyListeners(JChannel.java:1118)
    at org.jgroups.JChannel.notifyChannelConnected(JChannel.java:1104)
    at org.jgroups.JChannel.connect(JChannel.java:363)
    at org.jgroups.JChannel.connect(JChannel.java:352)
    at org.infinispan.remoting.transport.jgroups.JGroupsTransport.startJGroupsChannelIfNeeded(JGroupsTransport.java:554)
    at org.infinispan.remoting.transport.jgroups.JGroupsTransport.start(JGroupsTransport.java:478)
    at org.infinispan.remoting.transport.jgroups.CorePackageImpl$1.start(CorePackageImpl.java:42)
    at org.infinispan.remoting.transport.jgroups.CorePackageImpl$1.start(CorePackageImpl.java:27)
    at org.infinispan.factories.impl.BasicComponentRegistryImpl.invokeStart(BasicComponentRegistryImpl.java:617)
    at org.infinispan.factories.impl.BasicComponentRegistryImpl.doStartWrapper(BasicComponentRegistryImpl.java:608)
    at org.infinispan.factories.impl.BasicComponentRegistryImpl.startWrapper(BasicComponentRegistryImpl.java:577)
    at org.infinispan.factories.impl.BasicComponentRegistryImpl.access$700(BasicComponentRegistryImpl.java:30)
    at org.infinispan.factories.impl.BasicComponentRegistryImpl$ComponentWrapper.running(BasicComponentRegistryImpl.java:808)
    at org.infinispan.metrics.impl.MetricsCollector.start(MetricsCollector.java:70)
    at org.infinispan.metrics.impl.CorePackageImpl$1.start(CorePackageImpl.java:41)
    at org.infinispan.metrics.impl.CorePackageImpl$1.start(CorePackageImpl.java:34)
    at org.infinispan.factories.impl.BasicComponentRegistryImpl.invokeStart(BasicComponentRegistryImpl.java:617)
    at org.infinispan.factories.impl.BasicComponentRegistryImpl.doStartWrapper(BasicComponentRegistryImpl.java:608)
    at org.infinispan.factories.impl.BasicComponentRegistryImpl.startWrapper(BasicComponentRegistryImpl.java:577)
    at org.infinispan.factories.impl.BasicComponentRegistryImpl.access$700(BasicComponentRegistryImpl.java:30)
    at org.infinispan.factories.impl.BasicComponentRegistryImpl$ComponentWrapper.running(BasicComponentRegistryImpl.java:808)
    at org.infinispan.factories.impl.BasicComponentRegistryImpl.startDependencies(BasicComponentRegistryImpl.java:635)
    at org.infinispan.factories.impl.BasicComponentRegistryImpl.doStartWrapper(BasicComponentRegistryImpl.java:599)
    at org.infinispan.factories.impl.BasicComponentRegistryImpl.startWrapper(BasicComponentRegistryImpl.java:577)
    at org.infinispan.factories.impl.BasicComponentRegistryImpl.access$700(BasicComponentRegistryImpl.java:30)
    at org.infinispan.factories.impl.BasicComponentRegistryImpl$ComponentWrapper.running(BasicComponentRegistryImpl.java:808)
    at org.infinispan.factories.AbstractComponentRegistry.internalStart(AbstractComponentRegistry.java:354)
    at org.infinispan.factories.AbstractComponentRegistry.start(AbstractComponentRegistry.java:250)
    at org.infinispan.manager.DefaultCacheManager.internalStart(DefaultCacheManager.java:766)
    at org.infinispan.manager.DefaultCacheManager.start(DefaultCacheManager.java:734)
    at org.infinispan.server.SecurityActions.lambda$startCacheManager$1(SecurityActions.java:69)
    at org.infinispan.security.Security.doPrivileged(Security.java:56)
    at org.infinispan.server.SecurityActions.doPrivileged(SecurityActions.java:40)
    at org.infinispan.server.SecurityActions.startCacheManager(SecurityActions.java:72)
    at org.infinispan.server.Server.run(Server.java:398)
    at org.infinispan.server.Bootstrap.runInternal(Bootstrap.java:165)
    at org.infinispan.server.tool.Main.run(Main.java:98)
    at org.infinispan.server.Bootstrap.main(Bootstrap.java:50)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    at org.infinispan.server.loader.Loader.run(Loader.java:106)
    at org.infinispan.server.loader.Loader.main(Loader.java:51)