This plugin prevents players from placing lava blocks or emptying/filling buckets.
- StopLava.canUseLava Whether someone can place lava (lava block or bucket) (default: op).
- StopLava.canGetLava Permission to get lava in a bucket (default: true).
Source can be found at GitHub
When cancelling a PlayerBucketFillEvent, or PlayerBucketEmptyEvent the client is not notified of the event actually being cancelled. So the player will see the bucket being filled, while it isn't really. As will be clear when the player (dis)connects and gets the update.
For now this plugin is forcing a clumsy update to the client. Perhaps there are better ways to do this, but that seems to require use of the CraftBukkit API besides the Bukkit API.
I submitted a feature request to have CraftBukkit send the client these updates automatically.