This class lets you customise the about menu for Mac users (Java/JavaFX)

HandleAboutMac.java

// When you call new HandleAboutMac(), it will set the action on what has to be done when a Mac user selects the about menu
// in [your app name] > about [your app name]
public class HandleAboutMac  {
        public HandleAboutMac() {
            com.apple.eawt.Application application = com.apple.eawt.Application.getApplication();
            application.setAboutHandler(new AboutHandler() {
                @Override
                public void handleAbout(AppEvent.AboutEvent aboutEvent) {
                    // This is where your code goes for what has to be done when a Mac user selects the about menu
                    // For example:
                    JOptionPane.showMessageDialog(null, "YOUR APP NAME\nYOUR APP INFO");
                    
                    // If you want to use JavaFX, you'll need to use the Platform.runLater;
                    // Platform.runLater(new Runnable() {
                    //    @Override
                    //    public void run() {
                    //        // Your JFX code here
                    //    }
                    // });
                }
            });
        }
    }
    
    // Hope this helped!

With this java code, you can handle what has to be done when a Mac user goes to the about tab in your .jar program.
Leave a comment if this helped you :)