Reflection value is not output correctly

I'm currently working on a project and I decided to create a new Test project to understand where I fail. I recreate the classes that I'm using but in a simple way. My test project looks like this . And here you can find all the classes: ChunkGenerator ChunkGeneratorAbstact WorldChunkManager World Main And here's the output As you can see after using reflection and setting the WorldChunkManager to a custom one, I try to print out the UUID of the World ChunkManager, but for some reason I keep getting the original one instead of the custom one: