Update BlockItemPacketRewriter1_9.java

[Term4]

Problem
1.21.2, servers can update a single player-inventory slot via ClientboundSetPlayerInventory. ViaBackwards maps that to CONTAINER_SET_SLOT with window id -2

The 1.8 client's handleSetSlot only handles window -1, 0, and the oopen container's id. No -2 case, so these updates are silently dropped. This leads to the inventory only resyncing on a full window refresh (when a player opens and closes their inventory). Any server that uses this packet for inventorry updates (AHEM Minestom, but also some edge cases in vanilla, or custom vanilla servers) have this issue.

[Beaness]

Is this specifically 1.9 that started supporting this?
Also wouldn't the slot need different recalculation based on what window you have open (as the player inventory slot ids change I think)

[Term4]

Is this specifically 1.9 that started supporting this? Also wouldn't the slot need different recalculation based on what window you have open (as the player inventory slot ids change I think)

Updated! Also yes, I checked and it was specifically the 1.9 -> 1.8 rewriter. I sent those pics on discord unless you need them here too.

[Beaness]

Even though the server sends the slot count, the client only uses that slot count for dynamic inventories, I think for inventories like brewing stands, furnaces, ... it'd be better to have a hardcoded slot count that ignores the server send slot count (as that isn't used for slot recalculation)

[florianreuth]

Agreeing with @Beaness here, this should match the client's behavior.

[florianreuth]

Seems okay for me, thank you