code: void onHeartbeat(Member member, long timestamp) {
          if (!heartbeatAwareQuorumFunction) {
              return;
          }
          ((HeartbeatAware) quorumFunction).onHeartbeat(member, timestamp);
      }
docs: Notify a {@link HeartbeatAware} {@code QuorumFunction} that a heartbeat has been received from a member.
  
  @param member    source member
  @param timestamp heartbeat's timestamp