NPE in Topo2Jsonifier

2017-05-04 15:21:43,486 | WARN  | spatch-topology0 | ListenerRegistry                 | 125 - org.onosproject.onos-api - 1.10.0.SNAPSHOT | Exception encountered while processing event HostEvent{time=2017-05-04T15:21:43.443, type=HOST_REMOVED, subject=DefaultHost{id=00:AA:00:00:00:01/None, mac=00:AA:00:00:00:01, vlan=None, location=of:0000000000000204/6, ipAddresses=[10.0.2.2], annotations={}, configured=false}, prevSubject=null}
java.lang.NullPointerException
    at org.onosproject.ui.impl.topo.Topo2Jsonifier.addIps(Topo2Jsonifier.java:527)[158:org.onosproject.onos-gui:1.10.0.SNAPSHOT]
    at org.onosproject.ui.impl.topo.Topo2Jsonifier.json(Topo2Jsonifier.java:568)[158:org.onosproject.onos-gui:1.10.0.SNAPSHOT]
    at org.onosproject.ui.impl.topo.Topo2Jsonifier.json(Topo2Jsonifier.java:440)[158:org.onosproject.onos-gui:1.10.0.SNAPSHOT]
    at org.onosproject.ui.impl.topo.Topo2Jsonifier.jsonUiElement(Topo2Jsonifier.java:392)[158:org.onosproject.onos-gui:1.10.0.SNAPSHOT]
    at org.onosproject.ui.impl.topo.model.ModelCache.postEvent(ModelCache.java:105)[158:org.onosproject.onos-gui:1.10.0.SNAPSHOT]
    at org.onosproject.ui.impl.topo.model.ModelCache.removeHost(ModelCache.java:539)[158:org.onosproject.onos-gui:1.10.0.SNAPSHOT]
    at org.onosproject.ui.impl.topo.model.UiSharedTopologyModel$InternalHostListener.event(UiSharedTopologyModel.java:493)[158:org.onosproject.onos-gui:1.10.0.SNAPSHOT]
    at org.onosproject.ui.impl.topo.model.UiSharedTopologyModel$InternalHostListener.event(UiSharedTopologyModel.java:475)[158:org.onosproject.onos-gui:1.10.0.SNAPSHOT]
    at org.onosproject.event.ListenerRegistry.process(ListenerRegistry.java:66)[125:org.onosproject.onos-api:1.10.0.SNAPSHOT]
    at org.onosproject.event.impl.CoreEventDispatcher$DispatchLoop.process(CoreEventDispatcher.java:204)[127:org.onosproject.onos-core-net:1.10.0.SNAPSHOT]
    at org.onosproject.event.impl.CoreEventDispatcher$DispatchLoop.run(CoreEventDispatcher.java:187)[127:org.onosproject.onos-core-net:1.10.0.SNAPSHOT]
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)[:1.8.0_121]
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)[:1.8.0_121]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)[:1.8.0_121]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)[:1.8.0_121]
    at java.lang.Thread.run(Thread.java:745)[:1.8.0_121]