Trapdoors Cant be placed on upper half of block

When placing a trapdoor on the upper half of a block, it wont work. It just placing on the lower half, always the lower half. Its that how trapdoors work?

Steps to Reproduce

1. Get a Trapdoor
2. Place the trapdoor on upper half of a block (can be a random block)
3.The trapdoor should be place itself on the lower half of the block