Please add the following to your API, I would really appreciate it.

• Event that is fired when a tree is generated in the world
  • Method that returns HashMap<Location, Material> for what material was generated at what location
  • Method that returns String for the Object ID of what tree has been generated
• Event that is fired when an ore is placed in the world
  • Method that returns HashMap<Location, Material> for what material was generated at what location
  • Method that returns String for the Object ID of what ore has been generated

ores and trees no longer explicitly exist.

Those hashmaps sound horrible, but the rest is plausible.

But I'm sure we could do something with the same effect.

IMO, it shouldn't pass the buffer for trees.

Those events can be implemented, but will definitely be made stateless. If you want to change how those objects generate, implement Tree or extend Ore and insert your implementation into a registry, then use it in a pack. You shouldn't change behaviour invisibly, especially when there is a clear, supported, and expected way to do the same thing.

For the trees, an ImmutableBuffer could be implemented and passed to the event, but due to how ores generate it is impractical to re-generate them into a buffer. If you need to view the blocks, you can generate the Ore passed to the event in a dummy world.