1. Checkout https://github.com/GregHib/void-client in IntelliJ
2. Project Structure | Artifacts | Add | Jar -> From Modules with Dependencies
3. Set Main Class: Loader
4. Change MANIFEST.MF directory to ./void-client/ (default will be ./void-client/client/src)
5. OK
6. File | Build | Artifacts | void-client:jar | build

void-client.jar will be located in /out/artifacts/void_client_jar/

1. Update the RSA keys to match - modified-files
2. Disable the lobby by setting the initial login stage to 2 - modified-files
3. Fix the area sound packet from (id = 5, size = 6) to size = 8 - modified-files
4. Support java 6+ by skipping Runtime.load0 call - modified-files

Code changes can be found here however naming will likely differ in your deob client.