Concurent exception is thrown while processing aggregation

Sometimes (not always) exception is thrown while processing aggregation.
This causes that in resulting topology are not all nodes that meets specified criteria.

This exception is thrown:
Exception in thread "CommitFutures-4" java.lang.NullPointerException
at org.opendaylight.topoprocessing.impl.writer.TopologyWriter.onTransactionChainFailed(TopologyWriter.java:263)
at org.opendaylight.controller.md.sal.dom.broker.impl.PingPongTransactionChain$1.onTransactionChainFailed(PingPongTransactionChain.java:102)
at org.opendaylight.controller.cluster.databroker.DOMBrokerTransactionChain.transactionFailed(DOMBrokerTransactionChain.java:137)
at org.opendaylight.controller.cluster.databroker.DOMBrokerTransactionChain.access$100(DOMBrokerTransactionChain.java:30)
at org.opendaylight.controller.cluster.databroker.DOMBrokerTransactionChain$1.onFailure(DOMBrokerTransactionChain.java:98)
at com.google.common.util.concurrent.Futures$6.run(Futures.java:1310)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)