[Broker-J] Broker startup can fail due to ConcurrentModificationException

ERROR [VirtualHostNode-default-Config] (o.a.q.s.m.AbstractConfiguredObject) - Failed to open object with name 'default'.  Object will be put into ERROR state.
org.apache.qpid.server.configuration.IllegalConfigurationException: Cannot open virtual host message store:null
	at org.apache.qpid.server.virtualhost.AbstractVirtualHost.validateMessageStoreCreation(AbstractVirtualHost.java:563)
	at org.apache.qpid.server.virtualhost.AbstractVirtualHost.onValidate(AbstractVirtualHost.java:398)
	at org.apache.qpid.server.model.AbstractConfiguredObject.doValidation(AbstractConfiguredObject.java:1205)
	at org.apache.qpid.server.model.AbstractConfiguredObject$1.execute(AbstractConfiguredObject.java:589)
	at org.apache.qpid.server.model.AbstractConfiguredObject$1.execute(AbstractConfiguredObject.java:578)
	at org.apache.qpid.server.model.AbstractConfiguredObject$2.execute(AbstractConfiguredObject.java:639)
	at org.apache.qpid.server.model.AbstractConfiguredObject$2.execute(AbstractConfiguredObject.java:632)
	at org.apache.qpid.server.configuration.updater.TaskExecutorImpl$TaskLoggingWrapper.execute(TaskExecutorImpl.java:248)
	at org.apache.qpid.server.configuration.updater.TaskExecutorImpl$CallableWrapper$1.run(TaskExecutorImpl.java:320)
	at java.security.AccessController.doPrivileged(Native Method)
	at javax.security.auth.Subject.doAs(Subject.java:360)
	at org.apache.qpid.server.configuration.updater.TaskExecutorImpl$CallableWrapper.call(TaskExecutorImpl.java:313)
	at com.google.common.util.concurrent.TrustedListenableFutureTask$TrustedFutureInterruptibleTask.runInterruptibly(TrustedListenableFutureTask.java:125)
	at com.google.common.util.concurrent.InterruptibleTask.run(InterruptibleTask.java:57)
	at com.google.common.util.concurrent.TrustedListenableFutureTask.run(TrustedListenableFutureTask.java:78)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.qpid.server.bytebuffer.QpidByteBufferFactory.lambda$null$0(QpidByteBufferFactory.java:464)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.util.ConcurrentModificationException: null
	at java.util.Hashtable$Enumerator.next(Hashtable.java:1383)
	at java.util.HashMap.putMapEntries(HashMap.java:512)
	at java.util.HashMap.putAll(HashMap.java:785)
	at org.apache.qpid.server.model.AbstractConfiguredObject.getContextKeys(AbstractConfiguredObject.java:3508)
	at org.apache.qpid.server.store.berkeleydb.BDBUtils.getContextSettingsWithNameMatchingRegExpPattern(BDBUtils.java:130)
	at org.apache.qpid.server.store.berkeleydb.BDBUtils.getEnvironmentConfigurationParameters(BDBUtils.java:119)
	at org.apache.qpid.server.store.berkeleydb.StandardEnvironmentFacadeFactory$1.getParameters(StandardEnvironmentFacadeFactory.java:73)
	at org.apache.qpid.server.store.berkeleydb.StandardEnvironmentFacade.<init>(StandardEnvironmentFacade.java:116)
	at org.apache.qpid.server.store.berkeleydb.StandardEnvironmentFacadeFactory.createEnvironmentFacade(StandardEnvironmentFacadeFactory.java:89)
	at org.apache.qpid.server.store.berkeleydb.BDBMessageStore.doOpen(BDBMessageStore.java:57)
	at org.apache.qpid.server.store.berkeleydb.AbstractBDBMessageStore.openMessageStore(AbstractBDBMessageStore.java:131)
	at org.apache.qpid.server.virtualhost.AbstractVirtualHost.validateMessageStoreCreation(AbstractVirtualHost.java:559)
	... 18 common frames omitted