if (t == null) {
            throw new NoSuchElementException(clazz.getName());
        }
        return t;
    }

    private Service lookup(Class<? extends Service> c) {
        try {
            return lookup.lookup(c);
        } catch (LookupException e) {
            NoSuchElementException nsee = new NoSuchElementException(c.getName());
            e.initCause(e);
            throw nsee;
        }