Improving protection check for bucket usage

[RedstoneFuture]

Overview

Fixes #4851

The code change adds a specific block-filter to include only blocks that contain the "use" flag result in combination with "normal" bucket interactions. No waterlogging, no flooding allowed here, if it's not a plot-owner / member.

The new restriction was tested in-game.

Description

Improving protection check

We've had a bug with bucket handling in the past. This was fixed by removing the "use" flag request. Then we get a bug report for the "use" flag and dordsor re-added a similar "use" flag check in PR 4673.

Checking the "use" flag makes sense. However, there are blocks that are interactive(!), and waterloggable, or that drop when water is placed into the hitbox(!). We need to prevent that from happening.

Example: lever

• right click: interact, if the USE flag is set or you have build permissions
• shift + right click: place water (lever drops), only if you have build permissions

Since this interaction only involves CAULDRON types, I don't currently see a need for a separate flag to define the blocks.

Change of requested block

    public void onBucketFill(PlayerBucketFillEvent event) {
        Block block = event.getBlock();

In addition, I've adjusted the query here to target the block that was modified, which in this event is usually the same as the block being interacted with (the clicked block). It seems more logical to me to check here which block contains the final change.

• getClicketBLock = the interaction
• getBlock = the block for the final block change by bucket interaction (may be different for the PlayerBucketEmptyEvent and mostly the same for the PlayerBucketFillEvent)

Submitter Checklist

• Make sure you are opening from a topic branch (/feature/fix/docs/ branch (right side)) and not your main branch.
• Ensure that the pull request title represents the desired changelog entry.
• New public fields and methods are annotated with @since TODO.
• I read and followed the contribution guidelines.

[Copilot]

Pull request overview

This PR tightens PlotSquared’s bucket protection checks to prevent players from bypassing plot build restrictions by using buckets on blocks permitted by the use flag (e.g., levers), while still allowing intended bucket-based interactions for cauldrons.

Changes:

• Restricts use-flag-based bucket allowances to cauldron interactions only (to prevent waterlogging/flooding via interactable blocks).
• Adjusts the PlayerBucketFillEvent check to use event.getBlock() (the block considered for the protection query).

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[RedstoneFuture]

I used a different spelling; see the next commit.

[RedstoneFuture]

I used a different spelling; see the next commit.

[RedstoneFuture]

In theory, we should also allow minecraft:powder_snow_bucket here, event though the PlayerBucketEmptyEvent and PlayerBucketFillEvent aren't currently triggering by snow buckets at this time.

PaperMC/Paper#12239