The DragonBattle.initiateRespawn() function calls an NMS function, which checks if the 4 ender crystals are placed (as one would manually respawn the ender dragon), and only then proceeds to respawn the dragon using an different private NMS function.

Why is this? wouldn't it be better if it would actually just respawn the dragon (using the previously mentioned private function), or create a new function called respawn() ?

More info (and solution): https://www.spigotmc.org/threads/re-spawning-the-ender-dragon.255183/#post-2534599