While evaluating a GlassFish bug, I discovered a discrepancy in behavior of Class.getAnnotations() between IBM JRE and Sun JRE. the complex GlassFish issue boiled down to a simple test case as discussed below. The question is what should be the behavior of Class.getAnnotations() if one or more annotation class is not available at runtime. Consider the following test case:

// Main.java

import java.lang.annotation.*;

@Retention(RetentionPolicy.RUNTIME)
@interface Bar {}

@Bar
class Foo {}

class Main {
 public static void main(String[] args) throws Exception{
  Annotation[] as = Foo.class.getAnnotations();
  System.out.println("Found " + as.length + " no. of annotations");
 }
}

java Main

Exception in thread "main" java.lang.TypeNotPresentException: Type Bar not present
        at com.ibm.oti.reflect.AnnotationHelper.getAnnotation(AnnotationHelper.java:38)
        at com.ibm.oti.reflect.AnnotationHelper.getDeclaredAnnotations(AnnotationHelper.java:50)
        at java.lang.Class.getDeclaredAnnotations(Class.java:1628)
        at java.lang.Class.getAnnotations(Class.java:1589)
        at Main.main(Main.java:13)
Caused by: java.lang.ClassNotFoundException: Bar
        at java.lang.Class.forName(Class.java:169)
        at com.ibm.oti.reflect.AnnotationHelper.getAnnotation(AnnotationHelper.java:33)
        ... 4 more

Found 0 no. of annotations

I believe it is a bug in IBM JRE. There used to be a similar bug in Sun JDK. See http://bugs.sun.com/view_bug.do?bug_id=6322301 for details. It says that Class.getAnnotations() is supposed to ignore when a annotation type can't be loaded. Sun JDK has been fixed. Now time for IBM JDK to be fixed.