Spotless 8 for gradle fails with Java-Format 1.29.0 and JDK17

[YellowFlora]

Hello,

we are currently facing problems with Spotless together with the 1.29.0 release of Java-Format in our JDK17 repositories.

We are always getting errors like:

 src/main/java/org/sdase/commons/example/TestApp.java:LINE_UNDEFINED google-java-format(java.lang.NoClassDefFoundError) com/sun/tools/javac/tree/JCTree$JCAnyPattern (...)
 src/main/java/org/sdase/commons/example/TestPojo.java:LINE_UNDEFINED google-java-format(java.lang.NoClassDefFoundError) com/sun/tools/javac/tree/JCTree$JCAnyPattern (...)

Example repository:

SpotlessJavaFormatTest.zip

The errors appear only with JDK17 not with 21 and only since the Java-Format 1.29.0 Version.

Google itself writes in their release notes for that version:

The minimum support JDK version to run google-java-format is now JDK 21. Using google-java-format to format earlier versions of the language is still fully supported, but running the formatter itself on JDK 21 or newer is required.

I understand it like that JDK 17 should still working.

[jbduncan]

Sadly, Google is pretty clear here. You will need to do one of the following:

• Upgrade Java to 21 (which can be automated a bit with tools like OpenRewrite).
• Upgrade just the Java that your Gradle/Maven build runs on to 21, whilst using toolchains or the release or source compatibility flags with a value of Java 17.
• Hold off on upgrading to GJF 1.29.0 for now.

Since this is a decision made by the GJF maintainers, I'm afraid it's out of our hands. Sorry to be the bearer of bad news. :(

That being said, if I've misunderstood anything or if you'd like to discuss things further, feel free to reopen this issue!

[jbduncan]

For clarity, when Google say, "Using google-java-format to format earlier versions of the language is still fully supported", they mean that source code written for earlier versions of the Java language can still be formatted (which I guess includes all the way back to Java 8 or even earlier).

Since Java is good at backwards compatibility (a notable exception being the introduction of the JPMS in Java 9), this doesn't mean very much. You will still need to run GJF 1.29.0 on Java 21 or greater, even if it's used to format Java files compiled by Java 17.