private boolean catchEntryRefs(E entry) {
            strongRefs.clear();
            if (entry == null) {
                return true;
            }

            final List<? extends Reference<?>> refs = entry.getReferences();
            if (refs == null) {
                return true;
            }
            for (Reference<?> ref: refs) {
                final Object obj = ref.get();
                if (obj == null) {
                    strongRefs.clear();
                    return false;
                }
                strongRefs.add(obj);
            }
            return true;
        }