Pistons can delete plot walls

Server Implementation

Paper

Server Version

1.19

Describe the bug

Sticky pistons can be used to delete plot wall blocks.

Note: happens on 1.18.2 and presumably earlier versions as well.

https://user-images.githubusercontent.com/58818927/176791278-f442055d-3a6c-4d15-b08c-46555df58ed9.mov

To Reproduce

1. Place sticky piston at the edge of your plot pointing to the road.
2. Turn it into a headless piston using the debug stick (set the extended block property to true).
3. Update the piston by placing a block next to it.
4. Wall block disappears.

Expected behaviour

I expected the wall block to not disappear.

Screenshots / Videos

No response

Error log (if applicable)

No response

Plot Debugpaste

https://athion.net/ISPaster/paste/view/d44d61891e3c4dc98c2d26a1ed3e442b

PlotSquared Version

6.9.1-SNAPSHOT

Checklist

• I have included a Plot debugpaste.
• I am using the newest build from https://www.spigotmc.org/resources/77506/ and the issue still persists.

Anything else?

No response

Start by reproducing the sticky-piston sequence described in the issue on PlotSquared 6.9.1-SNAPSHOT, using the linked Plot debugpaste for context. Trace the plot-wall protection handling for piston block updates. Done means updating a headless sticky piston at a plot edge no longer deletes the wall block.