public ApplicationBuilder addRegistry(RegistryConfig registry) {
        if (this.registries == null) {
            this.registries = new ArrayList<>();
        }
        this.registries.add(registry);
        return getThis();
    }
@Test
    void addRegistry() {
        RegistryConfig registry = new RegistryConfig();
        ApplicationBuilder builder = new ApplicationBuilder();
        builder.addRegistry(registry);
        Assertions.assertNotNull(builder.build().getRegistry());
        Assertions.assertEquals(1, builder.build().getRegistries().size());
        Assertions.assertSame(registry, builder.build().getRegistry());
    }