There are multiple ways to add splash screen to Java application - https://docs.oracle.com/javase/tutorial/uiswing/misc/splashscreen.html

I tried adding it to application's jar file through `SplashScreen-Image` property.

Splashscreen got displayed as expected using standard Java launcher but was not displayed if the jar was launched by app launcher generated by jpackage.

Tested on Windows only. Not sure if the issue affects other Platforms.