CoAP Gateway shorten query identification

[TomazCebekAstron]

What would you like to be added or enhanced?

Emqx v5.0 feature request:
Currently every query is set as full name:
clientid
token
username
password
qos
retain

Make it possible to use single letter query identification :
clientid = c
token = t
username = u
password = p
qos = q
retain = r

So that the following commands can be transmited with a shorter packet size

connect command:

• original: coap-client -m post -e "" "coap://127.0.0.1/mqtt/connection?clientid=123&username=admin&password=public"
• proposed: coap-client -m post -e "" "coap://127.0.0.1/mqtt/connection?c=123&u=admin&p=public"

publish command:
-original: coap-client -m post -e "Hi, this is libcoap" "coap://127.0.0.1/ps/coap/test&clientid=123&token=3404490787"
-proposed: (on every publish we conserve 7(clientid=>c)+4(token => t) = 11 bytes)
coap-client -m post -e "Hi, this is libcoap" "coap://127.0.0.1/ps/coap%2Ftest&c=123&t=3404490787"

heartbeat command:

• original: coap-client -m put -e "" "coap://127.0.0.1/mqtt/connection?clientid=123&token=3404490787"
• proposed: coap-client -m put -e "" "coap://127.0.0.1/mqtt/connection?c=123&t=3404490787"

and so on...

Why is this needed?

The pdu sizes are becoming too big just for simple identification of a parameter...

[HJianBo]

Great suggestion! Thanks @TomazCebekAstron We will try to provide it in the near future