The system jar command always extracts into the current directory.

While this may be tolerable (albeit somewhat inconvenient) when executed from a shell or via `Process.exec` such that the current directory can be changed, it is not possible to control the output directory when the `jar` command is invoked via the `ToolProvider` SPI, as in
    var jarTool = ToolProvider.findFirst("jar");

The workaround is that one has to exec the command in order to set the output directory.