The following NPE has been seen when running the groupbasedpolicy POC demo:

2014-09-18 23:41:53,829 | ERROR | -notification-15 | NotifyTask | 163 - org.opendaylight.controller.sal-binding-broker-impl - 1.1.0.Helium-RC1-3-v201409190324 | Unhandled exception thrown by listener: org.opendaylight.controller.md.statistics.manager.StatisticsListener$$Broker$ListenerInvoker@58ad67b9
java.lang.IllegalArgumentException: Supplied class is not valid case [interface org.opendaylight.yang.gen.v1.urn.opendaylight.openflowplugin.extension.nicira.action.rev140714.group.desc.stats.updated.group.desc.stats.buckets.bucket.action.action.NxActionRegLoadNotifGroupDescStatsUpdatedCase]
at com.google.common.base.Preconditions.checkArgument(Preconditions.java:119)[78:com.google.guava:14.0.1]
at org.opendaylight.yangtools.binding.data.codec.impl.ChoiceNodeCodecContext.getStreamChild(ChoiceNodeCodecContext.java:96)[118:org.opendaylight.yangtools.binding-data-codec:0.6.2.Helium-RC1-3-v201409190324]
at org.opendaylight.yangtools.binding.data.codec.impl.BindingToNormalizedStreamWriter.enter(BindingToNormalizedStreamWriter.java:68)[118:org.opendaylight.yangtools.binding-data-codec:0.6.2.Helium-RC1-3-v201409190324]
at org.opendaylight.yangtools.binding.data.codec.impl.BindingToNormalizedStreamWriter.startCase(BindingToNormalizedStreamWriter.java:138)[118:org.opendaylight.yangtools.binding-data-codec:0.6.2.Helium-RC1-3-v201409190324]
at org.opendaylight.yang.gen.v1.urn.opendaylight.openflowplugin.extension.nicira.action.rev140714.group.desc.stats.updated.group.desc.stats.buckets.bucket.action.action.NxActionRegLoadNotifGroupDescStatsUpdatedCase$StreamWriter.serialize(DataObjectSerializerPrototype.java)[223:org.opendaylight.openflowplugin.extension-nicira:0.0.3.Helium-RC1-3-v201409190324]
at org.opendaylight.yangtools.binding.data.codec.impl.BindingNormalizedNodeCodecRegistry$DataObjectSerializerProxy.serialize(BindingNormalizedNodeCodecRegistry.java:214)[118:org.opendaylight.yangtools.binding-data-codec:0.6.2.Helium-RC1-3-v201409190324]
at org.opendaylight.yangtools.binding.data.codec.util.ChoiceDispatchSerializer.serialize(ChoiceDispatchSerializer.java:47)[118:org.opendaylight.yangtools.binding-data-codec:0.6.2.Helium-RC1-3-v201409190324]
at org.opendaylight.yang.gen.v1.urn.opendaylight.action.types.rev131112.action.list.Action$StreamWriter.serialize(DataObjectSerializerPrototype.java)[203:org.opendaylight.controller.model.flow-base:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.yang.gen.v1.urn.opendaylight.group.types.rev131018.group.buckets.Bucket$StreamWriter.serialize(DataObjectSerializerPrototype.java)[203:org.opendaylight.controller.model.flow-base:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.yang.gen.v1.urn.opendaylight.group.types.rev131018.group.Buckets$StreamWriter.serialize(DataObjectSerializerPrototype.java)[203:org.opendaylight.controller.model.flow-base:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.yang.gen.v1.urn.opendaylight.group.statistics.rev131111.group.desc.GroupDesc$StreamWriter.serialize(DataObjectSerializerPrototype.java)[205:org.opendaylight.controller.model.flow-statistics:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.yang.gen.v1.urn.opendaylight.group.statistics.rev131111.NodeGroupDescStats$StreamWriter.serialize(DataObjectSerializerPrototype.java)[205:org.opendaylight.controller.model.flow-statistics:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.yangtools.binding.data.codec.impl.BindingNormalizedNodeCodecRegistry$DataObjectSerializerProxy.serialize(BindingNormalizedNodeCodecRegistry.java:214)[118:org.opendaylight.yangtools.binding-data-codec:0.6.2.Helium-RC1-3-v201409190324]
at org.opendaylight.yangtools.binding.data.codec.util.AugmentableDispatchSerializer.emitAugmentation(AugmentableDispatchSerializer.java:73)[118:org.opendaylight.yangtools.binding-data-codec:0.6.2.Helium-RC1-3-v201409190324]
at org.opendaylight.yangtools.binding.data.codec.util.AugmentableDispatchSerializer.emitAugmentation(AugmentableDispatchSerializer.java:73)[118:org.opendaylight.yangtools.binding-data-codec:0.6.2.Helium-RC1-3-v201409190324]
at org.opendaylight.yangtools.binding.data.codec.util.AugmentableDispatchSerializer.serialize(AugmentableDispatchSerializer.java:53)[118:org.opendaylight.yangtools.binding-data-codec:0.6.2.Helium-RC1-3-v201409190324]
at org.opendaylight.yang.gen.v1.urn.opendaylight.group.types.rev131018.groups.Group$StreamWriter.serialize(DataObjectSerializerPrototype.java)[203:org.opendaylight.controller.model.flow-base:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.yangtools.binding.data.codec.impl.BindingNormalizedNodeCodecRegistry$DataObjectSerializerProxy.serialize(BindingNormalizedNodeCodecRegistry.java:214)[118:org.opendaylight.yangtools.binding-data-codec:0.6.2.Helium-RC1-3-v201409190324]
at org.opendaylight.yangtools.binding.data.codec.impl.BindingNormalizedNodeCodecRegistry.toNormalizedNode(BindingNormalizedNodeCodecRegistry.java:98)[118:org.opendaylight.yangtools.binding-data-codec:0.6.2.Helium-RC1-3-v201409190324]
at org.opendaylight.controller.md.sal.binding.impl.BindingToNormalizedNodeCodec.toNormalizedNode(BindingToNormalizedNodeCodec.java:56)[163:org.opendaylight.controller.sal-binding-broker-impl:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.controller.md.sal.binding.impl.AbstractWriteTransaction.merge(AbstractWriteTransaction.java:56)[163:org.opendaylight.controller.sal-binding-broker-impl:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.controller.md.sal.binding.impl.ForwardedBackwardsCompatibleDataBroker$ForwardedBackwardsCompatibleTransacion.putOperationalData(ForwardedBackwardsCompatibleDataBroker.java:220)[163:org.opendaylight.controller.sal-binding-broker-impl:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.controller.md.sal.binding.impl.ForwardedBackwardsCompatibleDataBroker$ForwardedBackwardsCompatibleTransacion.putOperationalData(ForwardedBackwardsCompatibleDataBroker.java:186)[163:org.opendaylight.controller.sal-binding-broker-impl:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.controller.md.statistics.manager.GroupDescStatsTracker.updateSingleStat(GroupDescStatsTracker.java:52)[218:org.opendaylight.controller.md.statistics-manager:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.controller.md.statistics.manager.GroupDescStatsTracker.updateSingleStat(GroupDescStatsTracker.java:28)[218:org.opendaylight.controller.md.statistics-manager:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.controller.md.statistics.manager.AbstractStatsTracker.updateStats(AbstractStatsTracker.java:107)[218:org.opendaylight.controller.md.statistics-manager:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.controller.md.statistics.manager.NodeStatisticsHandler.updateGroupDescStats(NodeStatisticsHandler.java:150)[218:org.opendaylight.controller.md.statistics-manager:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.controller.md.statistics.manager.StatisticsListener.onGroupDescStatsUpdated(StatisticsListener.java:76)[218:org.opendaylight.controller.md.statistics-manager:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.controller.md.statistics.manager.StatisticsListener$$Broker$ListenerInvoker.onNotification(StatisticsListener$$Broker$ListenerInvoker.java)[218:org.opendaylight.controller.md.statistics-manager:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.controller.sal.binding.impl.AbstractNotificationListenerRegistration.notify(AbstractNotificationListenerRegistration.java:38)[163:org.opendaylight.controller.sal-binding-broker-impl:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.controller.sal.binding.impl.AbstractNotificationListenerRegistration.notify(AbstractNotificationListenerRegistration.java:38)[163:org.opendaylight.controller.sal-binding-broker-impl:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.controller.sal.binding.impl.NotifyTask.run(NotifyTask.java:42)[163:org.opendaylight.controller.sal-binding-broker-impl:1.1.0.Helium-RC1-3-v201409190324]
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)[:1.7.0_65]
at java.util.concurrent.FutureTask.run(FutureTask.java:262)[:1.7.0_65]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)[:1.7.0_65]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)[:1.7.0_65]
at java.lang.Thread.run(Thread.java:745)[:1.7.0_65]

Thereafter, I see this:

2014-09-18 23:46:26,602 | ERROR | CommitFutures-0 | dedBackwardsCompatibleDataBroker | 163 - org.opendaylight.controller.sal-binding-broker-impl - 1.1.0.Helium-RC1-3-v201409190324 | Transaction DOM-659 failed to complete
TransactionCommitFailedException

{message=commit execution failed, errorList=[RpcError [message=commit execution failed, severity=ERROR, errorType=APPLICATION, tag=operation-failed, applicationTag=null, info=null, cause=java.lang.NullPointerException]]}

at org.opendaylight.controller.md.sal.dom.broker.impl.TransactionCommitFailedExceptionMapper.newWithCause(TransactionCommitFailedExceptionMapper.java:37)[160:org.opendaylight.controller.sal-broker-impl:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.controller.md.sal.dom.broker.impl.TransactionCommitFailedExceptionMapper.newWithCause(TransactionCommitFailedExceptionMapper.java:18)[160:org.opendaylight.controller.sal-broker-impl:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.yangtools.util.concurrent.ExceptionMapper.apply(ExceptionMapper.java:80)[81:org.opendaylight.yangtools.util:0.6.2.Helium-RC1-3-v201409190324]
at org.opendaylight.yangtools.util.concurrent.ExceptionMapper.apply(ExceptionMapper.java:31)[81:org.opendaylight.yangtools.util:0.6.2.Helium-RC1-3-v201409190324]
at org.opendaylight.yangtools.util.concurrent.MappingCheckedFuture.mapException(MappingCheckedFuture.java:60)[81:org.opendaylight.yangtools.util:0.6.2.Helium-RC1-3-v201409190324]
at org.opendaylight.yangtools.util.concurrent.MappingCheckedFuture.wrapInExecutionException(MappingCheckedFuture.java:64)[81:org.opendaylight.yangtools.util:0.6.2.Helium-RC1-3-v201409190324]
at org.opendaylight.yangtools.util.concurrent.MappingCheckedFuture.get(MappingCheckedFuture.java:77)[81:org.opendaylight.yangtools.util:0.6.2.Helium-RC1-3-v201409190324]
at com.google.common.util.concurrent.Uninterruptibles.getUninterruptibly(Uninterruptibles.java:135)[78:com.google.guava:14.0.1]
at com.google.common.util.concurrent.Futures$ChainingListenableFuture.run(Futures.java:846)[78:com.google.guava:14.0.1]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)[:1.7.0_65]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)[:1.7.0_65]
at java.lang.Thread.run(Thread.java:745)[:1.7.0_65]
Caused by: java.lang.NullPointerException
at org.opendaylight.yangtools.yang.data.impl.schema.nodes.AbstractImmutableNormalizedValueAttrNode.valueEquals(AbstractImmutableNormalizedValueAttrNode.java:57)[97:org.opendaylight.yangtools.yang-data-impl:0.6.2.Helium-RC1-3-v201409190324]
at org.opendaylight.yangtools.yang.data.impl.schema.nodes.AbstractImmutableNormalizedNode.equals(AbstractImmutableNormalizedNode.java:65)[97:org.opendaylight.yangtools.yang-data-impl:0.6.2.Helium-RC1-3-v201409190324]
at org.opendaylight.controller.md.sal.dom.store.impl.ResolveDataChangeEventsTask.resolveReplacedEvent(ResolveDataChangeEventsTask.java:163)[166:org.opendaylight.controller.sal-inmemory-datastore:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.controller.md.sal.dom.store.impl.ResolveDataChangeEventsTask.resolveNodeContainerChildUpdated(ResolveDataChangeEventsTask.java:221)[166:org.opendaylight.controller.sal-inmemory-datastore:1.1.0.Helium-RC1-3-v201409190324]
at org.opendaylight.controller.md.sal.dom.store.impl.ResolveDataChangeEventsTask.resolveNodeContainerReplaced(ResolveDataChangeEventsTask.java:188)[166:org.opendaylight.controller.sal-inmemory-datastore:1.1.0.Helium-RC1-3-v201409190324]

with the last part being repeated over and over