The build system does an automagic detection of java/javac/jar; if java is not installed, it ignores them, and if it's installed, it uses them. This support is needed for Android builds, but I'm not sure if jar support is always needed. If it isn't, we can forcibly disable Java support.
This should be force disabled not made an option.
If any can be duplicated or reproduce feel free to update summary and reopen please.