Following exception is thrown at the time a flow is being added in l2switch sample:

[_id=Uri [_value=openflow:64308846240835:2]]]]}], _payload=[0, -95, -79, -63, -47, -31, 0, -94, -78, -62, -46, -30, 8, 0, 69, 0, 0, 84, 0, 0, 64, 0, 64, 1, 37, -33, 10, 0, 0, 102, 10, 0, 0, 101, 8, 0, -41, 56, 11, -85, 14, -108, 86, -114, 97, 83, 0, 0, 0, 0, -!
119, -45, 6, 0, 0, 0, 0, 0, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55], augmentation=[]]
java.lang.NullPointerException: List node (urn:opendaylight:flow:inventory?revision=2013-08-19)instruction MUST contain leaf (urn:opendaylight:flow:inventory?revision=2013-08-19)order with value.
at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:235) ~[bundlefile:na]
at org.opendaylight.controller.md.sal.common.impl.util.compat.DataNormalizationOperation$ListItemNormalization.createBuilder(DataNormalizationOperation.java:267) ~[na:na]
at org.opendaylight.controller.md.sal.common.impl.util.compat.DataNormalizationOperation$CompositeNodeNormalizationOperation.normalize(DataNormalizationOperation.java:166) ~[na:na]
at org.opendaylight.controller.md.sal.common.impl.util.compat.DataNormalizationOperation$CompositeNodeNormalizationOperation.normalize(DataNormalizationOperation.java:195) ~[na:na]
at org.opendaylight.controller.md.sal.common.impl.util.compat.DataNormalizationOperation$CompositeNodeNormalizationOperation.normalize(DataNormalizationOperation.java:192) ~[na:na]
at org.opendaylight.controller.md.sal.common.impl.util.compat.DataNormalizationOperation$CompositeNodeNormalizationOperation.normalize(DataNormalizationOperation.java:195) ~[na:na]
at org.opendaylight.controller.md.sal.common.impl.util.compat.DataNormalizer.toNormalized(DataNormalizer.java:115) ~[na:na]
at org.opendaylight.controller.md.sal.common.impl.util.compat.DataNormalizer.toNormalized(DataNormalizer.java:76) ~[na:na]
at org.opendaylight.controller.md.sal.binding.impl.BindingToNormalizedNodeCodec.toNormalizedNode(BindingToNormalizedNodeCodec.java:62) ~[na:na]
at org.opendaylight.controller.md.sal.binding.impl.BindingToNormalizedNodeCodec.toNormalizedNode(BindingToNormalizedNodeCodec.java:55) ~[na:na]
at org.opendaylight.controller.md.sal.binding.impl.AbstractForwardedTransaction.doPutWithEnsureParents(AbstractForwardedTransaction.java:108) ~[na:na]
at org.opendaylight.controller.md.sal.binding.impl.ForwardedBackwardsCompatibleDataBroker$ForwardedBackwardsCompatibleTransacion.putConfigurationData(ForwardedBackwardsCompatibleDataBroker.java:236) ~[na:na]
at org.opendaylight.controller.md.sal.binding.impl.ForwardedBackwardsCompatibleDataBroker$ForwardedBackwardsCompatibleTransacion.putConfigurationData(ForwardedBackwardsCompatibleDataBroker.java:195) ~[na:na]
at org.opendaylight.controller.sample.l2switch.md.flow.FlowWriterServiceImpl.writeFlowToConfigData(FlowWriterServiceImpl.java:283) ~[bundlefile:na]
at org.opendaylight.controller.sample.l2switch.md.flow.FlowWriterServiceImpl.addMacToMacFlow(FlowWriterServiceImpl.java:112) ~[bundlefile:na]
at org.opendaylight.controller.sample.l2switch.md.flow.FlowWriterServiceImpl.addMacToMacFlowsUsingShortestPath(FlowWriterServiceImpl.java:146) ~[bundlefile:na]
at org.opendaylight.controller.sample.l2switch.md.packet.PacketHandler.handleEthernetPacket(PacketHandler.java:129) ~[bundlefile:na]
at org.opendaylight.controller.sample.l2switch.md.packet.PacketHandler.onPacketReceived(PacketHandler.java:87) ~[bundlefile:na]
at org.opendaylight.controller.sample.l2switch.md.packet.PacketHandler$$Broker$ListenerInvoker.onNotification(PacketHandler$$Broker$ListenerInvoker.java) [bundlefile:na]
at org.opendaylight.controller.sal.binding.impl.NotifyTask.call(NotifyTask.java:59) [bundlefile:na]
at java.util.concurrent.FutureTask.run(FutureTask.java:262) [na:1.7.0_55]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [na:1.7.0_55]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [na:1.7.0_55]
at java.lang.Thread.run(Thread.java:745) [na:1.7.0_55]