Add logging to CompiledJavaVersionBuildStep

This might help in determining the cause of
#31375

(cherry picked from commit c00f211)

core/deployment/src/main/java/io/quarkus/deployment/steps/CompiledJavaVersionBuildStep.java

@@ -11,37 +11,46 @@
 import java.nio.file.attribute.BasicFileAttributes;
 import java.util.concurrent.atomic.AtomicReference;
 
+import org.jboss.logging.Logger;
+
 import io.quarkus.deployment.annotations.BuildStep;
 import io.quarkus.deployment.pkg.builditem.BuildSystemTargetBuildItem;
 import io.quarkus.deployment.pkg.builditem.CompiledJavaVersionBuildItem;
 
 public class CompiledJavaVersionBuildStep {
 
+    private static final Logger log = Logger.getLogger(CompiledJavaVersionBuildStep.class);
+
     /**
      * Determines the Java version by looking up the major version of the first successfully parsed
      * application .class file that is found
      */
     @BuildStep
     public CompiledJavaVersionBuildItem compiledJavaVersion(BuildSystemTargetBuildItem buildSystemTarget) {
         if ((buildSystemTarget.getOutputDirectory() == null) || (!Files.exists(buildSystemTarget.getOutputDirectory()))) {
+            log.debug("Skipping because output directory does not exist");
             // needed for Arquillian TCK tests
             return CompiledJavaVersionBuildItem.unknown();
         }
         AtomicReference<Integer> majorVersion = new AtomicReference<>(null);
         try {
+            log.debugf("Walking directory '%s'", buildSystemTarget.getOutputDirectory().toAbsolutePath().toString());
             Files.walkFileTree(buildSystemTarget.getOutputDirectory(), new SimpleFileVisitor<>() {
                 @Override
                 public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
                     if (file.getFileName().toString().endsWith(".class")) {
+                        log.debugf("Checking file '%s'", file.toAbsolutePath().toString());
                         try (InputStream in = new FileInputStream(file.toFile())) {
                             DataInputStream data = new DataInputStream(in);
                             if (0xCAFEBABE == data.readInt()) {
                                 data.readUnsignedShort(); // minor version -> we don't care about it
-                                majorVersion.set(data.readUnsignedShort());
+                                int v = data.readUnsignedShort();
+                                majorVersion.set(v);
+                                log.debugf("Determined compile java version to be %d", v);
                                 return FileVisitResult.TERMINATE;
                             }
-                        } catch (IOException ignored) {
-
+                        } catch (IOException e) {
+                            log.debugf(e, "Encountered exception while processing file '%s'", file.toAbsolutePath().toString());
                         }
                     }
                     // if this was not .class file or there was an error parsing its contents, we continue on to the next file
@@ -52,6 +61,7 @@ public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
 
         }
         if (majorVersion.get() == null) {
+            log.debug("No .class files located");
             return CompiledJavaVersionBuildItem.unknown();
         }
         return CompiledJavaVersionBuildItem.fromMajorJavaVersion(majorVersion.get());