Callback when a heartbeat has come or gone

[StareStarrySky]

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The necessity of two new Properties named onHeartbeatIn and onHeartbeatOut likely add into the Client CLASS, when a heartbeat has come or gone?

I want to show a blinking light means heartbeat ping and pong, however there's no problem if don't have this function for me.
Wait for other conditions if exist and necessary.