When a green power device (GPD) communicates with Proxy/Sink, it seems good to have MAC ACK to ensure the communication robustness like unicast in ZigBee PRO. However, I saw that all communications between GPD and Proxy are broadcasts in EmberZNet, where MAC ACK makes little or no sense. I saw somewhere mentioned that MAC ACK is optional for green power. Is MAC ACK for green power communication implemented for EmberZNet v18.104.22.168? Or MAC ACK for green power is nonsense.