assertNotNull(b2a);
        SingletonContainer.Bean2 b2b = injector.getInstance(SingletonContainer.Bean2.class);
        assertNotNull(b2b);
        assertNotEquals(b2a.num, b2b.num);
    }

    static class SingletonContainer {
        private static final AtomicInteger bean1 = new AtomicInteger();
        private static final AtomicInteger bean2 = new AtomicInteger();

        @Named
        @Singleton

    def "getNames"() {
        expect:
        container.getNames().isEmpty()

        when:
        container.add(new Bean("bean1"))
        container.add(new Bean("bean2"))
        container.add(new Bean("bean3"))
        then:
        container.names == ["bean1", "bean2", "bean3"] as SortedSet
    }

    def "returns null element with name is not present and there are no rules to create it"() {
        expect: