/viaversion dump Output

https://dump.viaversion.com/84e55e7cbb460fb0808fa7b3883c007ef61e0692ba0fada34b37331f67bd411a

Server/Client Error

N/A

Bug Description

When joining <=1.12.2 servers, the wall "up" state is handled incorrectly

Suspected code causing the issue: (WallConnectionHandler#getStates(WrappedBlockData)

In 1.12.2's code, it checked if there was also air above the wall to evaluate the UP value

Steps to Reproduce

Join a 1.12.2 server
Place some walls down with blocks on the sides of them

Notice the "up" state is incorrect

1.12.2

1.21.11

Additional Server Info

No response

Checklist

• Via plugins are only running on EITHER the backend servers (e.g. Paper) OR the proxy (e.g. Velocity), not on both.
• I have included a ViaVersion dump.
• If applicable, I have included a paste (not a screenshot) of the error.
• I have tried the latest build(s) from https://ci.viaversion.com/ and the issue still persists.