KAPT: Run tests on JDK 21

Previously, some tests have also been disabled on JDK 11+, since
we did not filter out empty filesets, which led to failed assertion
inside JDK.
 #KT-57389

plugins/kapt3/kapt3-base/src/org/jetbrains/kotlin/kapt3/base/annotationProcessing.kt

@@ -304,7 +304,7 @@ fun KaptContext.parseJavaFiles(javaSourceFiles: List<File>): JavacList<JCTree.JC
 }
 
 private fun KaptContext.initModulesIfNeeded(files: JavacList<JCTree.JCCompilationUnit>): JavacList<JCTree.JCCompilationUnit> {
-    if (isJava9OrLater()) {
+    if (files.isNotEmpty() && isJava9OrLater()) {
         val initModulesMethod = compiler.javaClass.getMethod("initModules", JavacList::class.java)
 
         @Suppress("UNCHECKED_CAST")