Spotless formats code differently between JDK versions (17 vs 21)

[MarkEWaite]

We've seen cases in the Jenkins project use of spotless formatting where a comment adjacent to a case statement inside a switch will be formatted on Java 17 with a different indentation than on Java 21, even though the Java version is declared as Java 17 in the Maven project using Spotless.

A recent example is:

• Bump org.jenkins-ci:jenkins from 1.131 to 1.132 jenkinsci/winstone#436

When we move the comment so that it is either inside the case or outside the switch, then the Java version dependent formatting does not happen.

[nedtwigg]

I'm sure this bug is real, but it is almost definitely a bug in the formatter you are using in Spotless, rather than in Spotless itself. So either googleJavaFormat or eclipse, depending on which one you are using.

When we move the comment so that it is either inside the case or outside the switch, then the platform dependent formatting does not happen.

That is a useful and actionable bug report for whichever formatter you are using through Spotless.

[basil]

@nedtwigg I think the problem is in Spotless itself; see #2447 (comment).

[nedtwigg]

my summary of that comment

• yes, if you don't specify a version for a formatter, Spotless picks the latest available which will run on the JVM you are using
• if you want the same behavior on development environments running on multiple JRE versions, you will need to set the version explicitly
• looking at the source-level of the project for JVM_SUPPORT calculations is a neat idea, but plumbing that out would be a significant task. I'm open to a PR which adds it, but I bet just pinning a specific version is going to way more bang for your buck