NPE in BDB Store

Currently org.infinispan.loaders.bdbje.BdbjeCacheStore#prepare does next things:
1) Create transaction in currentTransaction
2) Retrieve it from currentTransaction
3) Remove all transactions from currentTransaction.

This leads to race condition when one thread can do (3) between (1) and (2) in another thread. This produces:
org.infinispan.loaders.CacheLoaderException: Problem preparing transaction
at org.infinispan.loaders.bdbje.BdbjeCacheStore.convertToCacheLoaderException(BdbjeCacheStore.java:589)
at org.infinispan.loaders.bdbje.BdbjeCacheStore.prepare(BdbjeCacheStore.java:315)
at org.infinispan.loaders.bdbje.BdbjeCacheStore.prepare(BdbjeCacheStore.java:274)
at org.infinispan.interceptors.CacheStoreInterceptor.prepareCacheLoader(CacheStoreInterceptor.java:289)
at org.infinispan.interceptors.CacheStoreInterceptor.visitPrepareCommand(CacheStoreInterceptor.java:199)
at org.infinispan.commands.tx.PrepareCommand.acceptVisitor(PrepareCommand.java:133)
at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:116)
at org.infinispan.interceptors.base.CommandInterceptor.handleDefault(CommandInterceptor.java:130)
at org.infinispan.commands.AbstractVisitor.visitPrepareCommand(AbstractVisitor.java:126)
at org.infinispan.commands.tx.PrepareCommand.acceptVisitor(PrepareCommand.java:133)
at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:116)
at org.infinispan.interceptors.EntryWrappingInterceptor.visitPrepareCommand(EntryWrappingInterceptor.java:93)
at org.infinispan.commands.tx.PrepareCommand.acceptVisitor(PrepareCommand.java:133)
at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:116)
at org.infinispan.interceptors.locking.AbstractTxLockingInterceptor.invokeNextAndCommitIf1Pc(AbstractTxLockingInterceptor.java:120)
at org.infinispan.interceptors.locking.OptimisticLockingInterceptor.visitPrepareCommand(OptimisticLockingInterceptor.java:131)
at org.infinispan.commands.tx.PrepareCommand.acceptVisitor(PrepareCommand.java:133)
at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:116)
at org.infinispan.interceptors.NotificationInterceptor.visitPrepareCommand(NotificationInterceptor.java:58)
at org.infinispan.commands.tx.PrepareCommand.acceptVisitor(PrepareCommand.java:133)
at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:116)
at org.infinispan.interceptors.TxInterceptor.visitPrepareCommand(TxInterceptor.java:106)
at org.infinispan.commands.tx.PrepareCommand.acceptVisitor(PrepareCommand.java:133)
at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:116)
at org.infinispan.interceptors.StateTransferLockInterceptor.handleWithRetries(StateTransferLockInterceptor.java:213)
at org.infinispan.interceptors.StateTransferLockInterceptor.visitPrepareCommand(StateTransferLockInterceptor.java:85)
at org.infinispan.commands.tx.PrepareCommand.acceptVisitor(PrepareCommand.java:133)
at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:116)
at org.infinispan.interceptors.base.CommandInterceptor.handleDefault(CommandInterceptor.java:130)
at org.infinispan.commands.AbstractVisitor.visitPrepareCommand(AbstractVisitor.java:126)
at org.infinispan.commands.tx.PrepareCommand.acceptVisitor(PrepareCommand.java:133)
at org.infinispan.interceptors.base.CommandInterceptor.invokeNextInterceptor(CommandInterceptor.java:116)
at org.infinispan.interceptors.InvocationContextInterceptor.handleAll(InvocationContextInterceptor.java:132)
at org.infinispan.interceptors.InvocationContextInterceptor.handleDefault(InvocationContextInterceptor.java:91)
at org.infinispan.commands.AbstractVisitor.visitPrepareCommand(AbstractVisitor.java:126)
at org.infinispan.commands.tx.PrepareCommand.acceptVisitor(PrepareCommand.java:133)
at org.infinispan.interceptors.InterceptorChain.invoke(InterceptorChain.java:345)
at org.infinispan.transaction.TransactionCoordinator.prepare(TransactionCoordinator.java:140)
at org.infinispan.transaction.TransactionCoordinator.prepare(TransactionCoordinator.java:122)
at org.infinispan.transaction.xa.TransactionXaAdapter.commit(TransactionXaAdapter.java:120)
at org.apache.geronimo.transaction.manager.TransactionImpl.commitResource(TransactionImpl.java:688)
at org.apache.geronimo.transaction.manager.TransactionImpl.commit(TransactionImpl.java:304)
at org.apache.geronimo.transaction.manager.TransactionManagerImpl.commit(TransactionManagerImpl.java:250)
at sun.reflect.GeneratedMethodAccessor65.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)[:1.6.0_24]
at java.lang.reflect.Method.invoke(Method.java:616)[:1.6.0_24]
at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:309)[71:org.springframework.aop:3.0.6.RELEASE]
at org.springframework.osgi.service.importer.support.internal.aop.ServiceInvoker.doInvoke(ServiceInvoker.java:58)[73:org.springframework.osgi.core:1.2.1]
at org.springframework.osgi.service.importer.support.internal.aop.ServiceInvoker.invoke(ServiceInvoker.java:62)[73:org.springframework.osgi.core:1.2.1]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)[71:org.springframework.aop:3.0.6.RELEASE]
at org.springframework.aop.support.DelegatingIntroductionInterceptor.doProceed(DelegatingIntroductionInterceptor.java:131)[71:org.springframework.aop:3.0.6.RELEASE]
at org.springframework.aop.support.DelegatingIntroductionInterceptor.invoke(DelegatingIntroductionInterceptor.java:119)[71:org.springframework.aop:3.0.6.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)[71:org.springframework.aop:3.0.6.RELEASE]
at org.springframework.osgi.service.util.internal.aop.ServiceTCCLInterceptor.invokeUnprivileged(ServiceTCCLInterceptor.java:56)[73:org.springframework.osgi.core:1.2.1]
at org.springframework.osgi.service.util.internal.aop.ServiceTCCLInterceptor.invoke(ServiceTCCLInterceptor.java:39)[73:org.springframework.osgi.core:1.2.1]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)[71:org.springframework.aop:3.0.6.RELEASE]
at org.springframework.osgi.service.importer.support.LocalBundleContextAdvice.invoke(LocalBundleContextAdvice.java:59)[73:org.springframework.osgi.core:1.2.1]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)[71:org.springframework.aop:3.0.6.RELEASE]
at org.springframework.aop.support.DelegatingIntroductionInterceptor.doProceed(DelegatingIntroductionInterceptor.java:131)[71:org.springframework.aop:3.0.6.RELEASE]
at org.springframework.aop.support.DelegatingIntroductionInterceptor.invoke(DelegatingIntroductionInterceptor.java:119)[71:org.springframework.aop:3.0.6.RELEASE]
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)[71:org.springframework.aop:3.0.6.RELEASE]
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:202)[71:org.springframework.aop:3.0.6.RELEASE]
at $Proxy57.commit(Unknown Source)[:]
at org.infinispan.CacheImpl.executeCommandAndCommitIfNeeded(CacheImpl.java:1016)[808:org.infinispan.core:5.1.6.FINAL]
at org.infinispan.CacheImpl.put(CacheImpl.java:702)[808:org.infinispan.core:5.1.6.FINAL]
at org.infinispan.CacheImpl.put(CacheImpl.java:694)[808:org.infinispan.core:5.1.6.FINAL]
at org.infinispan.CacheSupport.put(CacheSupport.java:53)[808:org.infinispan.core:5.1.6.FINAL]
at com.ubs.ace.quickfix.store.InfinispanStore.updateNextTargetMsgSeqNum(InfinispanStore.java:89)[807:com.ubs.ace.quickfix-engine:1.0.0]
at com.ubs.ace.quickfix.store.InfinispanStore.incrNextTargetMsgSeqNum(InfinispanStore.java:85)[807:com.ubs.ace.quickfix-engine:1.0.0]
at quickfix.SessionState.incrNextTargetMsgSeqNum(SessionState.java:368)[811:org.apache.servicemix.bundles.quickfix:1.5.2.1]
at quickfix.Session.next(Session.java:974)[811:org.apache.servicemix.bundles.quickfix:1.5.2.1]
at quickfix.mina.SingleThreadedEventHandlingStrategy$SessionMessageEvent.processMessage(SingleThreadedEventHandlingStrategy.java:114)[811:org.apache.servicemix.bundles.quickfix:1.5.2.1]
at quickfix.mina.SingleThreadedEventHandlingStrategy.block(SingleThreadedEventHandlingStrategy.java:77)[811:org.apache.servicemix.bundles.quickfix:1.5.2.1]
at quickfix.mina.SingleThreadedEventHandlingStrategy$1.run(SingleThreadedEventHandlingStrategy.java:94)[811:org.apache.servicemix.bundles.quickfix:1.5.2.1]
at java.lang.Thread.run(Thread.java:679)[:1.6.0_24]
Caused by: java.lang.NullPointerException
at java.util.concurrent.ConcurrentHashMap.put(ConcurrentHashMap.java:909)[:1.6.0_24]
at org.infinispan.loaders.bdbje.BdbjeCacheStore.prepare(BdbjeCacheStore.java:312)
... 73 more