Sam reports in private email hitting this in netvirt CSITs under Karaf 4: "I see the below exception repeating over and over. i think that is causing
most of the csit failures right now."

This looks similar to NETVIRT-706 but a fix for that one was merged, so there's more:

2017-06-16 08:37:10,001 | INFO | nPool-1-worker-1 | IdManager

AsyncDataTreeChangeListenerBase | 238 -
org.opendaylight.genius.mdsalutil-api - 0.3.0.SNAPSHOT | Thread
terminated due to uncaught exception:
AsyncDataTreeChangeListenerBase-DataTreeChangeHandler-0
java.lang.NullPointerException
at org.opendaylight.netvirt.fibmanager.VrfEntryListener.lambda$createLocalFibEntry$5(VrfEntryListener.java:750)[302:org.opendaylight.netvirt.fibmanager-impl:0.5.0.SNAPSHOT]
at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1374)[:1.8.0_131]
at java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:580)[:1.8.0_131]
at org.opendaylight.netvirt.fibmanager.VrfEntryListener.createLocalFibEntry(VrfEntryListener.java:747)[302:org.opendaylight.netvirt.fibmanager-impl:0.5.0.SNAPSHOT]
at org.opendaylight.netvirt.fibmanager.VrfEntryListener.createFibEntries(VrfEntryListener.java:428)[302:org.opendaylight.netvirt.fibmanager-impl:0.5.0.SNAPSHOT]
at org.opendaylight.netvirt.fibmanager.VrfEntryListener.add(VrfEntryListener.java:235)[302:org.opendaylight.netvirt.fibmanager-impl:0.5.0.SNAPSHOT]
at org.opendaylight.netvirt.fibmanager.VrfEntryListener.add(VrfEntryListener.java:148)[302:org.opendaylight.netvirt.fibmanager-impl:0.5.0.SNAPSHOT]
at org.opendaylight.genius.datastoreutils.AsyncDataTreeChangeListenerBase$DataTreeChangeHandler.run(AsyncDataTreeChangeListenerBase.java:157)[238:org.opendaylight.genius.mdsalutil-api:0.3.0.SNAPSHOT]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)[:1.8.0_131]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)[:1.8.0_131]
at java.lang.Thread.run(Thread.java:748)[:1.8.0_131]
2017-06-16 08:37:10,002 | INFO | nPool-1-worker-2 | UpdateIdEntryJob