PUBREL packet - Publish release (QoS 2, part 2).
MQTT 5.0 §3.6
Readonly
Packet identifier
Optional
PUBREL properties (5.0)
Reason code (5.0, defaults to 0x00)
Packet type discriminator.
PUBREL packet - Publish release (QoS 2, part 2).
See
MQTT 5.0 §3.6