exp
Player's current level experience points.
This field contains experience on current level, to get total player experience use totalExp. Be careful with this field! To change experience value better to use giveExp and takeExp. To set total player experience use totalExp. New experience value shouldn't be less than 0 and bigger than maximal possible XP on current level.
For implementation: Better to add argument value validation to your implementation because new value can be bigger than maximal possible experience on current level, and you must trim it to the limit.
Return
Current level experience points or 0 if player has no exp
Throws
If player-related object not exists