Anti Xray bug on certain chunk formats

Expected behavior

everything works fine

Observed/Actual behavior

Unexpected palette resize in ChunkPacketBlockControllerAntiXray

Steps/models to reproduce

When there are two identical block state in a certain section's palette, such as deepslate and deepslate[axis=y] below. These files might be created by some third party softwares.

Then the values passed in this constructor would have two same blockstates

When presetValue is added as the second-to-last element, the palette size at that point is 32 (containing 31 unique states and 1 duplicate state). When presetValue is added as the last element, the calculation of newBits ignores the duplicate element, causing the set that should have 33 elements to be reduced to 32. As a result, the palette resizing cannot be triggered during chunk loading.

Ultimately, when being processed by ChunkPacketBlockControllerAntiXray, the last element that failed to be added results in No Resize Expected.

Plugin and Datapack List

none

Paper version

1.21.11-DEV-c5a2736

Other

No response

Start at ChunkPacketBlockControllerAntiXray and trace the palette resizing calculation described in the report. Reproduce the case with duplicate block states, including deepslate and deepslate[axis=y], and verify that adding the preset value triggers resizing when the palette reaches the relevant size without dropping an element.