When add elan interface cache throwing NPE, The NPE in class ElanInterfaceCache.java method add(), The NPE detail information as follows:

2020-01-08T02:52:17,878 | ERROR | opendaylight-cluster-data-notification-dispatcher-50 | DataTreeChangeListenerActor | 229 - org.opendaylight.controller.sal-clustering-commons - 1.11.0.SNAPSHOT | member-2-shard-default-config: Error notifying listener org.opendaylight.genius.mdsalutil.cache.DataObjectCache$$Lambda$1489/0x000000010134b840@330b9fab
java.lang.NullPointerException: null
at org.opendaylight.netvirt.elan.cache.ElanInterfaceCache.added(ElanInterfaceCache.java:76) ~[?:?]
at org.opendaylight.netvirt.elan.cache.ElanInterfaceCache.added(ElanInterfaceCache.java:37) ~[?:?]
at org.opendaylight.genius.mdsalutil.cache.DataObjectCache.lambda$new$0(DataObjectCache.java:92) ~[264:org.opendaylight.genius.mdsalutil-api:0.8.0.SNAPSHOT]
at org.opendaylight.controller.md.sal.binding.impl.BindingDOMDataTreeChangeListenerAdapter.onDataTreeChanged(BindingDOMDataTreeChangeListenerAdapter.java:43) ~[224:org.opendaylight.controller.sal-binding-broker-impl:1.11.0.SNAPSHOT]