Available lua packages for Dovecot / Push notification to EGroupware

I am trying to integrate a push notification using lua from EGroupware

. In the Mailcow/Dovecot container, I see a lua-cjson module but not lua-json which is required by their lua notification script.

dovecot-lua/now 2:2.3.17-3+debian10 amd64 [installed,local]
liblua5.1-0/now 5.1.5-8.1+b2 amd64 [installed,local]
liblua5.3-0/now 5.3.3-1.1 amd64 [installed,local]
lua-bitop/now 1.0.2-5 amd64 [installed,local]
lua-cjson/now 2.1.0+dfsg-2.1 amd64 [installed,local]
lua-socket/now 3.0~rc1+git+ac3201d-4 amd64 [installed,local]
lua-sql-mysql/now 2.3.4-1+b1 amd64 [installed,local]

While I do understand, that one cannot provide all the lua json variant there is, why cjson

which is rather old has been picked up? I guess I cannot install the missing plugin without been removed by the next update.

On top of that, I have difficulties to load the necessary plugins using extra.conf because of the order:
doveconf: Warning: /etc/dovecot/extra.conf line 1: Global setting mail_plugins won't change the setting inside an earlier filter at /etc/dovecot/dovecot.conf line 175 (if this is intentional, avoid this warning by moving the global setting before /etc/dovecot/dovecot.conf line 175)

Maybe someone can help me for any of the two issues?

Thanks.