Adding an associatable bean to another bean simply adds a triple pointing to it. The getAssociationsFor call filters by RDF type. Hence the following snippet fails:

CETBean cetBean; // any cet bean will do
AnnotationBeanUtil abu = new AnnotationBeanUtil(beanSession);
AnnotationBean annotationBean = new AnnotationBean();
abu.register(annotationBean);

abu.addAnnotationTo(cetBean, annotationBean);
abu.getAnnotationsFor(cetBean); // returns nothing

How to fix it? The best way is to not filter by RDF type or explicitly set the rdf type. I suggest the former.