Reported by Oliver Kopp, a maintainer of JabRef (https://github.com/koppor/):

In JDK24, when on macOS, using jpackage, and building a DMG, there is
the possibility to provide a .properties file using
"--file-associations". There I have "icon=jabref.icns". When building
with JDK24, everything works fine. With JDK25, I get
"java.nio.file.NoSuchFileException: jabref.icns".

In JDK25, when giving a relative path from the directory where
jpackage is called, it works.

The icon file is placed in the same directory as the ".properties"
file. - I think, the path given in the .properties file should be
resolved relatively from the path of that file - and not from the
directory where jpackage is started.