2018-05-21T14:37:46,428 | ERROR | org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.natservice.rev160111.napt.switches.RouterToNaptSwitch_AsyncDataTreeChangeListenerBase-DataTreeChangeHandler-0 | AsyncDataTreeChangeListenerBase  | 276 - org.opendaylight.genius.mdsalutil-api - 0.5.0.SNAPSHOT | Thread terminated due to uncaught exception: org.opendaylight.yang.gen.v1.urn.opendaylight.netvirt.natservice.rev160111.napt.switches.RouterToNaptSwitch_AsyncDataTreeChangeListenerBase-DataTreeChangeHandler-0
java.lang.NullPointerException: null
	at org.opendaylight.netvirt.natservice.ha.NatDataUtil.updateRouterMap(NatDataUtil.java:26) [376:org.opendaylight.netvirt.natservice-impl:0.7.0.SNAPSHOT]
	at org.opendaylight.netvirt.natservice.ha.SnatCentralizedSwitchChangeListener.update(SnatCentralizedSwitchChangeListener.java:77) [376:org.opendaylight.netvirt.natservice-impl:0.7.0.SNAPSHOT]
	at org.opendaylight.netvirt.natservice.ha.SnatCentralizedSwitchChangeListener.update(SnatCentralizedSwitchChangeListener.java:32) [376:org.opendaylight.netvirt.natservice-impl:0.7.0.SNAPSHOT]
	at org.opendaylight.genius.datastoreutils.AsyncDataTreeChangeListenerBase$DataTreeChangeHandler.run(AsyncDataTreeChangeListenerBase.java:176) [276:org.opendaylight.genius.mdsalutil-api:0.5.0.SNAPSHOT]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [?:?]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [?:?]
	at java.lang.Thread.run(Thread.java:748) [?:?]