HBASE-11992 introduces a feature that allows user to plugin the replication endpoint while specifying the Replication peer configurations. This feature is introduced in 0.98.9 version. As this feature introduces new data that is written to zk nodes there are some limitations/things to be noted when we have lower 0.98 versions across clusters. The feature adds the replication endpoint Impl class name, the peer node related data and the configurations associated with the peer node to the peerId znode under the peers znode in zookeeper. So any peer running on the older version of 0.98 would be unable to parse this data and would not be able to use the customized replication end point. It would continue to go with the default replication behaviour as before this feature. So in order to make use of this feature, it is recommended that the all the clusters involved in the replication are updated to 0.98.9+ versions.