Java is the original version from Mojang/Notch. There’s always been enough of a community that killing it off to move away from Java would break so many extensions and servers would see an active revolt.

There is the non-Java version (Bedrock), but that’s not nearly as extensible.

While you meant Minecraft here, to shock you further, please enjoy this:

https://en.wikipedia.org/wiki/Microsoft_Java_Virtual_Machine