@Override
                        public void run(final Status status) {
                            onRpcReturned(Replicator.this.id, RequestType.AppendEntries, status, header,
                                getResponse(), seq, stateVersion, monotonicSendTimeMs);
                        }
Send probe or heartbeat request
@param isHeartbeat      if current entries is heartbeat
@param heartBeatClosure heartbeat callback
jraft-core/src/main/java/com/alipay/sofa/jraft/core/Replicator.java