[1.12.2]How can I know whether a chunk is generated (and saved to .mcr file) or not?

[BillStark001]

I'm trying to make a mod that can transfer a world's data from a low version to a world using the same seed in a high version, so that player activities is able to save and new features can be introduced.

Basically I'm planning to find chunks needs to be copied to the new version and copy them chunk-wisely. Checking if a chunk needs to be copied is simple - just contrast it to the chunk in the same coordinates in a new-generated world to see if it's changed, copying chunks is also simple, BUT first I need to find chunks that are already generated on which I got into trouble.

It's not realistic to contrast each chunk in the world(or a part of it) for that's extremely time-and-space-consuming(I think that I may cause chunk generation by getting the info. of a non-generated chunk using Forge API), so it's necessary to find all generated chunks.

I'm new at Minecraft modding. Thanks to your help.

[Cadiboo]

World gen has changed a lot over time, I think if you want to have mod that provides this your best bet would be to grab the world datafixers from all versions & condense them