When testing latest jpackage EA build 14-jpackage+1-49 on macOS 10.15 (19A582a) warning ""Terminal.app" wants access to control "Finder.app"" was shown while generating DMG package. This warning was shown only once and after clicking "OK" button DMG got generated without errors and was working fine. Subsequent runs did not show this warning message.
See attached image for warning dialog.

To reproduce it:
1) Download latest jpackage build.
2) Remove quarantine flag
sudo xattr -dr com.apple.quarantine /PathToJDK/jdk-14.jdk
3) jpackage --package-type dmg --input input --dest output --name Test --main-jar DynamicTreeDemo.jar --main-class webstartComponentArch.DynamicTreeApplication