Question from Takatoshi on MQTT Comments list
I have a comment about the following part of MQTT Version 5.0 document:
If the value of Request Problem Information is 0, the Server MAY return a Reason String or User Properties on a CONNACK or DISCONNECT packet, but MUST NOT send a Reason String or User Properties on any packet other than PUBLISH, CONNACK, or DISCONNECT [MQTT-3.1.2-29]. If the value is 0 and the Client receives a Reason String or User Properties in a packet other than PUBLISH, CONNACK, or DISCONNECT, it uses a DISCONNECT packet with Reason Code 0x82 (Protocol Error) as described in section 4.13 Handling errors.
At first, the spec refer to CONNACK and DISCONNECT. But from the middle, PUBLISH is mixed.
Which MQTT control packets can use Reason String and/or User
Properties if Request Problem Information is 0 ?