I tried this too. After replacing the MANIFEST.MF in the with-dependencies.jar with the MANIFEST.MF from the /target/classes/META_INF folder I changed the .jar extension into .urcap. While installing it in Polyscope a .jar file is being created in the hidden folder ursim/.urcaps and a warning occurs in the terminal of Polyscope with the following information:
Failed to install artifact: /home/ubuntu/Downloads/ursim-3.4.3-77/.urcaps/com.mycompany.myurcap.jar: org.osgi.framework.BundleException: The bundle file:/home/ubuntu/Downloads/ursim-3.4.3-77/.urcaps/com.mycompany.myurcap.jar does not have a META-INF/MANIFEST.MF! Make sure, META-INF and MANIFEST.MF are the first 2 entries in your JAR!.
I checked the .jar file in the /.urcaps folder and it definitely has a MANIFEST.MF (identical to the one from target/classes/META_INF) inside the /META-INF folder.
Do you think the problem might be that these are not the FIRST 2 entries (alphabetically) in the jar file, because there is the /com folder before the the /META-INF folder? Inside the jar file are the folders /com, /META-INF, /org, /OSGI-OPT and two files about.html, LICENSE
Thank you for your help and patience!