Issue description
If this option is checked, the block behaves like ladders and vines (mobs can climb this block provided it's not full and they're colliding with a solid wall)
The required code (at least for 1.12.2) is:
@Override
public boolean isLadder(IBlockState state, IBlockAccess world, BlockPos pos, EntityLivingBase entity) {
return true;
}
I will consider adding this option.