Subscribe_changed_param_int

Hi. I use subscribe_changed_param_int to listen for parameter changes from a client.

shared_ptr<ParamServer> paramServer = make_shared<ParamServer>(_serverComponent);
paramServer->subscribe_changed_param_int([&](ParamServer::IntParam param) {
        cout << "Param changed: " << param.name << endl;
});

I can handle parameter change, but in the client I see log messages like this:

[12:03:04|Warn ] sending again after 0.509952 s, retries to do: 3  (512). (mavlink_command_sender.cpp:309)
[12:03:04|Warn ] Request was for msg ID: 242 (mavlink_command_sender.cpp:315).

So how can I acknowledge parameter change from the server side?