17-07-10 20:40:26,747 | ERROR | ool-214-thread-5 | NaptEventHandler | 342 - org.opendaylight.netvirt.natservice-impl - 0.4.1.SNAPSHOT | NAT Service :Exception in NaptEventHandler.handleEvent() payload org.opendaylight.netvirt.natservice.internal.NAPTEntryEvent@4a83c660
java.lang.NullPointerException: the Function passed to Optional.transform() must not return null.
at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:226)[38:com.google.guava:18.0.0]
at com.google.common.base.Present.transform(Present.java:71)[38:com.google.guava:18.0.0]
at org.opendaylight.netvirt.natservice.internal.NatUtil.getExtGwMacAddFromRouterId(NatUtil.java:1525)[342:org.opendaylight.netvirt.natservice-impl:0.4.1.SNAPSHOT]
at org.opendaylight.netvirt.natservice.internal.NaptEventHandler.handleEvent(NaptEventHandler.java:193)[342:org.opendaylight.netvirt.natservice-impl:0.4.1.SNAPSHOT]
at org.opendaylight.netvirt.natservice.internal.NaptPacketInHandler$1.run(NaptPacketInHandler.java:139)[342:org.opendaylight.netvirt.natservice-impl:0.4.1.SNAPSHOT]

Stable/Carbon CSIT karaf console log: https://logs.opendaylight.org/releng/jenkins092/netvirt-csit-1node-openstack-newton-nodl-v2-upstream-stateful-carbon/807/odl1_karaf.log.gz