I am smart enough to find that there is an achievement "Stack Overflow" with a description "It's full of stars!", but I seem to be not smart enough to find anything on how to get this achievement. I tried messing with withers, nether stars and beacons, but had no luck. Also I couldn't find it in code.
I would like to know whether this achievement is obtainable and if so, how.

Well, this texture seems to have some stars: https://github.com/OpenMods/OpenBlocks/blob/master/src/main/resources/assets/openblocks/textures/items/devzerooverzero.png

You sir are genius!
Got it!