MalformedParametersException on Oracle Java 8 with code compiled with JDK21 and later

[bric3]

Clearly this issue is a bit niche! This message is just a small heads up in case anyone hits this situation.

The issue is that code compiled with JDK21 and later can fail when accessing parameters via reflection in Oracle 1.8 u471 (the last update at this time), this code raises a MalformedParametersException. This can hit tools that "walk" methods or constructors like Byte Buddy.

Indeed, from JDK 21 (JDK-8292275), the compiler properly flag method parameters as synthetic (or mandate), however this has a side effect when the parameter names are accessed reflectively (via Executable::getParameters) on Oracle 1.8 u471.

A fix (via JDK-8058322) has been made and merged in Oct 2024 and as such is included in OpenJdk 8u since then, but at the time of this writing Oracle JDK 1.8 appear to not have it.

So the workaround are:

• Use -parameters which may add some overhead
• Use a different compiler, e.g. JDK 17.
• Bump the JDK
• Use another OpenJDK distribution

I put up a tad more in this reproducer project : https://github.com/bric3/malformed-parameters-oracle-8

[raphw]

Thanks, I added a safety mechanism for this case, so it will not break Byte Buddy. Likely this will be irrelevant data for most people anyways.

[bric3]

Agreed, it's niche. I'll reach out to Oracle and see if they can land the patch.

I feel a bit alone though when I hit that one.