anchor.diff:  - `discovery.zen.fd.register_connection_listener`
   - `discovery.zen.join_retry_attempts`
   - `discovery.zen.join_retry_delay`
  +- `discovery.zen.join_timeout`
   - `discovery.zen.max_pings_from_another_master`
   - `discovery.zen.send_leave_request`
   - `discovery.zen.master_election.wait_for_joins_timeout`
  
positive.code: - `discovery.zen.ping.unicast.concurrent_connects`
  - `discovery.zen.ping.unicast.hosts.resolve_timeout`
  - `discovery.zen.ping.unicast.hosts`
  - `discovery.zen.unsafe_rolling_upgrades_enabled`
  - `discovery.zen.commit_timeout`
  - `discovery.zen.fd.connect_on_network_disconnect`
  - `discovery.zen.fd.ping_interval`
  - `discovery.zen.fd.ping_timeout`
  
negative.code: *Impact* +
  Discontinue use of the `discovery.zen` settings. Specifying these settings in
  `elasticsearch.yml` will result in an error on startup.
  ====
  