The implementation of JavaType.toJavaName() in JVMCI returns the wrong Java name for a lambda class. Example:

Supplier<Runnable> lambda = () -> () -> System.out.println("run");
ResolvedJavaType lambdaType = metaAccess.lookupJavaType(lambda.getClass());
lambdaType.toJavaName(); // returns wrong name here

This has been fixed in later JDKs with a JVMCI update via JDK-8225810 (JDK 14) which seems a lot more risky to backport than just the changes to MetaUtil.java which are only used internal to JVMCI.

Thus, I'm proposing to only backport MetaUtil.java changes from JDK-8225810 to OpenJDK 11u as it fixes a debuginfo generation issue in GraalVM/Mandrel.