I'm a budding developer building a simple Spigot plugin to distribute and I'm trying to do my homework on licenses. As an act of good faith, I'm compiling all the licenses for all the libraries that I use. So, what exactly is the license for Spigot? I'm looking at their repo and noting Bukkit is GPL and CraftBukkit is LGPL, but Spigot itself has no LICENSE.txt that I can find. I assume it's probably a version of GPL due to the copyleft in Bukkit but I want to be sure.