It doesn't necessarily reduce the jar size, since by default the dependency scope is "compile" and are not shaded into the jar, thus supplied at runtime. However, since this is good practice for a maven dependency and I'm always looking for ways to improve my knowledge of maven, I'll merge this.

I'm actually shading the CommandAPI into my plugin jar and I noticed it was a little large after updating the version. I looked in the jar and found that bukkit along with brigadier was shaded into it.

In this case with spigot, the bukkit and brigadier code is provided when the plugin is loaded so there's no need to include it

I see! Thanks for clarifying!