Java 8 Compatibility

[liammacisaac]

Are you looking to keep JSign compatible with Java 8 in the 6.1 release? I've noticed that there's something breaking in there which works fine with Java 21, specifically when using microsoft trusted signing. The pom still has source/target = 8 though which makes me think that this is an oversight.

If you can confirm that you want to keep Java 8 support in this version, I'll raise an issue, investigate a bit further and submit a PR to fix it.

[ebourg]

Yes I intend to preserve the Java 8 compatibility, ideally until Java 8 is EOL everywhere. What issue did you notice?

[liammacisaac]

I didn't have much time to look into the issue, but taking a look now, I've realised it's user error. My IntelliJ had defaulted to JDK21 for the project so I was running code compiled on JDK 21 with a V8 JRE. The main class that causes an issue here is ByteBuffer because some of the methods that previously inherited from Buffer (e.g. flip() in this case) now have overridden implementations in ByteBuffer that return a ByteBuffer object. This then causes JDK8 to throw a NoSuchMethodError at runtime. So, as long as it's compiled with Java 8 there's no issue with compatibility from 8-21.

[ebourg]

Ah yes that's a common issue, it could be avoided by building with the -release 8 flag but that doesn't work for Jsign. With this option the compiler no longer recognizes the javax.smartcardio package used for the PIV and OpenPGP cards (JDK-8212638), nor the internal packages such as sun.security.pkcs11.wrapper which is used for configuring the PKCS#11 libraries.

I don't mind adding some casts around the ByteBuffer calls to avoid this issue.

[liammacisaac]

Just to wrap this up, I'm OK with how this works at the moment now knowing what I did wrong.