The Bug:

Tree leaves can grow through walls.

Steps to Reproduce:

1. Summon a wall and a nearby azalea by using the commands provided below.

   /fill ~1 ~ ~1 ~1 ~10 ~15 minecraft:stone

   /setblock ~-1 ~ ~8 minecraft:clay

   /setblock ~-1 ~1 ~8 minecraft:azalea

2. Obtain some bone meal and apply it to the azalea.
3. If the azalea leaves didn't grow through the wall, replant another azalea and try again.
4. Take note as to whether or not tree leaves can grow through walls.

Observed Behavior:

Tree leaves can grow through walls.

Expected Behavior:

Tree leaves would not be able to grow through walls.