Issues parsing source with a local interface

[shrugalic]

We recently upgraded from Java 17 to Java 21. Apparently the JavaParser has a problem with switch over a sealed type.

• spotless 6.25.0 or 7.0.0.BETA1
• cleanthat 2.21

Error Message

There is no such thing as a local interface. Pay attention that this feature is supported starting from 'JAVA_16' language level. If you need that feature the language level must be configured in the configuration before parsing the source files.
Not able to parse path='Sample.java' with com.github.javaparser.JavaParser@200c1143

Code

public class Sample {
	void sample() {
		interface ISample {
			void iSample();
		}
	}
}

How we include cleanthat into our build

We do specify Java 21 where we include cleanthat:

cleanthat()
    .version("2.21")
    .sourceCompatibility("21")
    .addMutator("SafeButNotConsensual")
    .excludeMutator("UseUnderscoresInNumericLiterals")
    .excludeMutator("AvoidInlineConditionals")

I should probably also mention that cleanthat was updated to include JavaParser v3.26.1 following the issue #817

Maybe I should open a JavaParser issue instead?

Edit: Oh, there already is one: javaparser/javaparser#3990

Edit 2: That issue also mentions that the main developers of JavaParser are no longer active, and that there may be more up-to-date alternatives. This comment is marked as abuse though 🤔, so the link does not open the comment directly): It mentions this post which uses talks about https://github.com/congo-cc/congo-parser-generator