How do you prepare jar file for Invoke Java Method

I have been unsuccessful for two days to Invoke a method in any other jar file except the one provided on the UiPath sample download (“Object.jar”). I did however discover that if I double click on the Object.jar file which I can successfully use with UiPath I get an “Invalid or corrupt jarfile” from the JVM Launcher. On the files that DO NOT WORK with UiPath invoke method it doesn’t complain at all when I double click. So I am assuming that at minimum it cannot be an executable java. What other requirements are there for preparing a jar file for to be usable to call a method within UiPath?

Invoke Java Method Download