I've done this in my addCollisionBoxToList() method:
AxisAlignedBB aabb = new AxisAlignedBB(x1, y1, z1, x2, y2, z2);
addCollisionBoxToList(pos, p_185477_4_, p_185477_5_, aabb);
super.addCollisionBoxToList(state, worldIn, pos, p_185477_4_, p_185477_5_, p_185477_6_);
But it's not working. It is still one block high. And if I don't call the super method it just has no bounding box at all. I've printed the positions to make sure that they are in the correct positions in the world.
What else am I supposed to do?
Never mind, got it working! I was prematurely adding the position to my aabb's coordinates, which messed up the positioning.