NPE during message serialization

The following was seen when running the Group Based Policy application:

2014-09-16 06:59:01.477 PDT [pool-22-thread-3] WARN o.o.g.r.ofoverlay.flow.FlowTable - FLOW: Uri [_value=intraallow|10] Flow [_hardTimeout=0, _id=Uri [_value=intraallow|10], _idleTimeout=0, _instructions=Instructions [_instruction=[Instruction [_instruction=ApplyActionsCase [_applyActions=ApplyActions [_action=[Action [_action=NxActionOutputRegNodesNodeTableFlowApplyActionsCase [_nxOutputReg=NxOutputReg [_maxLen=65535, _src=Src [_ofsNbits=31, _srcChoice=SrcNxRegCase [_nxReg=class org.opendaylight.yang.gen.v1.urn.opendaylight.openflowjava.nx.match.rev140421.NxmNxReg7, augmentation=[]], augmentation=[]], augmentation=[]], augmentation=[]], _key=ActionKey [_order=0], _order=0, augmentation=[]]], augmentation=[]], augmentation=[]], _key=InstructionKey [_order=0], _order=0, augmentation=[]]], augmentation=[]], _key=FlowKey [_id=Uri [_value=intraallow|10]], _match=Match [augmentation=[GeneralAugMatchNodesNodeTableFlow [_extensionList=[ExtensionList [_extension=Extension [augmentation=[NxAugMatchNodesNodeTableFlow [_nxmNxReg=NxmNxReg [_reg=class org.opendaylight.yang.gen.v1.urn.opendaylight.openflowjava.nx.match.rev140421.NxmNxReg0, _value=10, augmentation=[]]]]], _extensionKey=class org.opendaylight.yang.gen.v1.urn.opendaylight.openflowplugin.extension.nicira.match.rev140714.NxmNxReg0Key, _key=ExtensionListKey [_extensionKey=class org.opendaylight.yang.gen.v1.urn.opendaylight.openflowplugin.extension.nicira.match.rev140714.NxmNxReg0Key], augmentation=[]], ExtensionList [_extension=Extension [augmentation=[NxAugMatchNodesNodeTableFlow [_nxmNxReg=NxmNxReg [_reg=class org.opendaylight.yang.gen.v1.urn.opendaylight.openflowjava.nx.match.rev140421.NxmNxReg2, _value=10, augmentation=[]]]]], _extensionKey=class org.opendaylight.yang.gen.v1.urn.opendaylight.openflowplugin.extension.nicira.match.rev140714.NxmNxReg2Key, _key=ExtensionListKey [_extensionKey=class org.opendaylight.yang.gen.v1.urn.opendaylight.openflowplugin.extension.nicira.match.rev140714.NxmNxReg2Key], augmentation=[]]]]]], _priority=65000, _tableId=3, _barrier=false, augmentation=[]]
2014-09-16 06:59:01.559 PDT [nioEventLoopGroup-11-3] WARN o.o.o.protocol.impl.core.OFEncoder - Message serialization failed
java.lang.NullPointerException: null
at org.opendaylight.openflowjava.nx.codec.action.RegLoadCodec.serialize(RegLoadCodec.java:32) ~[na:na]
at org.opendaylight.openflowjava.nx.codec.action.RegLoadCodec.serialize(RegLoadCodec.java:19) ~[na:na]
at org.opendaylight.openflowjava.protocol.impl.util.ListSerializer.serializeList(ListSerializer.java:39) ~[bundlefile:na]
at org.opendaylight.openflowjava.protocol.impl.serialization.instruction.AbstractActionInstructionSerializer.serialize(AbstractActionInstructionSerializer.java:47) ~[bundlefile:na]
at org.opendaylight.openflowjava.protocol.impl.serialization.instruction.AbstractActionInstructionSerializer.serialize(AbstractActionInstructionSerializer.java:30) ~[bundlefile:na]
at org.opendaylight.openflowjava.protocol.impl.util.ListSerializer.serializeList(ListSerializer.java:39) ~[bundlefile:na]
at org.opendaylight.openflowjava.protocol.impl.serialization.factories.FlowModInputMessageFactory.serialize(FlowModInputMessageFactory.java:56) ~[bundlefile:na]
at org.opendaylight.openflowjava.protocol.impl.serialization.factories.FlowModInputMessageFactory.serialize(FlowModInputMessageFactory.java:32) ~[bundlefile:na]
at org.opendaylight.openflowjava.protocol.impl.serialization.SerializationFactory.messageToBuffer(SerializationFactory.java:36) ~[bundlefile:na]
at org.opendaylight.openflowjava.protocol.impl.core.OFEncoder.encode(OFEncoder.java:41) [bundlefile:na]
at org.opendaylight.openflowjava.protocol.impl.core.OFEncoder.encode(OFEncoder.java:26) [bundlefile:na]
at io.netty.handler.codec.MessageToByteEncoder.write(MessageToByteEncoder.java:107) [bundlefile:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:658) [bundlefile:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:716) [bundlefile:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:651) [bundlefile:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.write(AbstractChannelHandlerContext.java:637) [bundlefile:4.0.23.Final]
at io.netty.channel.DefaultChannelPipeline.write(DefaultChannelPipeline.java:880) [bundlefile:4.0.23.Final]
at io.netty.channel.AbstractChannel.write(AbstractChannel.java:230) [bundlefile:4.0.23.Final]
at org.opendaylight.openflowjava.protocol.impl.connection.ChannelOutboundQueue.flush(ChannelOutboundQueue.java:189) [bundlefile:na]
at org.opendaylight.openflowjava.protocol.impl.connection.ChannelOutboundQueue.access$000(ChannelOutboundQueue.java:40) [bundlefile:na]
at org.opendaylight.openflowjava.protocol.impl.connection.ChannelOutboundQueue$1.run(ChannelOutboundQueue.java:84) [bundlefile:na]
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:351) [bundlefile:4.0.23.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:350) [bundlefile:4.0.23.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:116) [bundlefile:4.0.23.Final]
at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:137) [bundlefile:4.0.23.Final]
at java.lang.Thread.run(Thread.java:745) [na:1.7.0_65]

The application programs 58 flows on each of the two nodes. One node gets all 58, and the other gets 57 out of 58.