The Bug

The new wall connections added in 20w15a let light pass through in configurations where there is no visible gap.

Steps to Reproduce

• Summon a hollow box of blocks around you.

  /fill ~-10 ~-1 ~-10 ~10 ~6 ~10 minecraft:polished_diorite hollow
  

• Take note of the light level of your surroundings.
• Replace the walls of the box with andesite walls.

  /fill ~-10 ~ ~-10 ~10 ~5 ~10 minecraft:andesite_wall replace minecraft:polished_diorite
  

• Observe the light level of your surroundings and take note as to whether or not walls allow light to pass through them.

Observed Behavior

Walls allow light to pass through them.

Expected Behavior

Walls would not allow light to pass through them.