OAK-3398 : make lease update more robust by checking state and leaseEnd properties are unchanged when updating the lease - if they are have changed then that can only be done by another instance in the cluster which was declaring this instance as timed out - and in that case the local instance should gracefully step back, aka handleLeaseFailure, oak-core stop
jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/document/ClusterNodeInfo.java