code: public static boolean hasAnnotation(CtClass clazz, String annotationName) {
          ClassFile cf = clazz.getClassFile2();
          AnnotationsAttribute ainfo = (AnnotationsAttribute)
              cf.getAttribute(AnnotationsAttribute.invisibleTag);
          AnnotationsAttribute ainfo2 = (AnnotationsAttribute)
              cf.getAttribute(AnnotationsAttribute.visibleTag);
          return checkAnnotation(ainfo, ainfo2, annotationName);
      }
docs: Returns true if the given class has an annotation set with the given name, returns false otherwise.