Add isParentFirst method to QuarkusClassLoader

    This can be used by extensions to determine if a class
    would be loaded parent first or not.
    Relates to: quarkusio/quarkus#16576 (comment)

dataset/GitHub_Java/quarkusio.quarkus/independent-projects/bootstrap/core/src/main/java/io/quarkus/bootstrap/classloading/QuarkusClassLoader.java

@@ -88,7 +88,7 @@ public class QuarkusClassLoader extends ClassLoader implements Closeable {
     private volatile boolean driverLoaded;
 
     private QuarkusClassLoader(Builder builder) {
-        super(builder.parent);
+        super(new GetPackageBlockingClassLoader(builder.parent));
         this.name = builder.name;
         this.elements = builder.elements;
         this.bannedElements = builder.bannedElements;
@@ -117,6 +117,32 @@ private String sanitizeName(String name) {
         return name;
     }
 
+    /**
+     * Returns true if the supplied class is a class that would be loaded parent-first
+     */
+    public boolean isParentFirst(String name) {
+        if (name.startsWith(JAVA)) {
+            return true;
+        }
+
+        //even if the thread is interrupted we still want to be able to load classes
+        //if the interrupt bit is set then we clear it and restore it at the end
+        boolean interrupted = Thread.interrupted();
+        try {
+            ClassLoaderState state = getState();
+            synchronized (getClassLoadingLock(name)) {
+                String resourceName = sanitizeName(name).replace(".", "/") + ".class";
+                return parentFirst(resourceName, state);
+            }
+
+        } finally {
+            if (interrupted) {
+                //restore interrupt state
+                Thread.currentThread().interrupt();
+            }
+        }
+    }
+
     private boolean parentFirst(String name, ClassLoaderState state) {
         return parentFirst || state.parentFirstResources.contains(name);
     }
@@ -354,7 +380,7 @@ public InputStream getResourceAsStream(String unsanitisedName) {
      * @param name
      * @return
      */
-    @Override
+    //@Override
     protected Class<?> findClass(String moduleName, String name) {
         try {
             return loadClass(name, false);
@@ -706,4 +732,23 @@ static final class ClassLoaderState {
         }
     }
 
+    /**
+     * Horrible JDK8 hack
+     *
+     * getPackage() on JDK8 will always delegate to the parent, so QuarkusClassLoader will never define a package,
+     * which can cause issues if you then try and read package annotations as they will be from the wrong ClassLoader.
+     *
+     * We add this ClassLoader into the mix to block the getPackage() delegation.
+     */
+    private static class GetPackageBlockingClassLoader extends ClassLoader {
+
+        protected GetPackageBlockingClassLoader(ClassLoader parent) {
+            super(parent);
+        }
+
+        @Override
+        protected Package getPackage(String name) {
+            return null;
+        }
+    }
 }