the wall of stars is also definetly not part of the void. The name originates from a flavour source, one of the oldest "complete" and "accurate" descriptions of the make up of the cosmos, the Codex Dimensionis, by Sir Francis of Madrid, astronomer, philosopher, occultist and most importantly, researcher of the makeup of the universe, ca. 1600. He spend most of the later half of his life with research into teleportation, portals, magical gates, etc and for many of the spheres, was one of the first humans (that we know of) who succesfully entered all of the places mentioned in the description apart from the worlds core and alternate universes, which he only speculated might exist, and returned alive to write about it. As an astronomer, you can imagine his reaction when he first made it into the hull of the cosmos, whatever you may call it, and found it to be black, and filled with glowing balls of light.
"By the gods, it's full of stars."
And thus the foundation for the naming was made. Not having the tools and knowledge at hand to know any better, he lived and died in the firm believe that the stars we see in the night-sky were projections of what he found in that part of the cosmos.
Of course the entire cosmos model is about as accurate as the model of chemistry that shows atoms as different colored balls with sticks between them. Which is to say, for humans, it's entirely sufficent. If gods would try to explain the actual state of affairs, even Will would have problems wrapping his mind around it.