caimingchao

@tomaswolf In my case, i will keep retrying to establish a connection to the server until it succeeds. so I overwrite some methods to do that, but I'm not sure...

[heartbeat code](https://github.com/apache/mina-sshd/blob/de46a157c4ce9a9d070fd781d70530dad9141e50/sshd-core/src/main/java/org/apache/sshd/client/session/ClientConnectionService.java#L121) According to the default configuration, the withReply variable seems to always be True