New feature added, now Paper or it's fork server can use the sign function to detect translation keys to know whether a player is using a specified mod or not. (PS: It's also easy to hide this kind of info, so please don't think this is a magic plugin to get rid of all the cheaters) And you need to add below content in your config.yml to use new feature:
# Extra optional detections
# WARNING:
# This sign translation detection depends on sign editor API availability.
# On some older server versions/APIs it is NOT available and will be skipped automatically.
extra-detections:
sign-translation:
enabled: true
mods:
Freecam:
detect:
key: "key.freecam.toggle"
punishment:
action: "KICK"
reason: "&c&lWarning: Please do not use &b&lFreecam &c&lon this server."
AccurateBlockPlacement:
detect:
key: "key.category.accurateblockplacement.category"
punishment:
action: "KICK"
reason: "&c&lWarning: Please do not use &b&lAccurateBlockPlacement &c&lon this server."