when:
        def extension = Mock(TestExtension)
        storage.add(typeOf(TestExtension), "ext", extension)

        and:
        storage.configureExtension("ext", {
            it.call(1)
        })
        storage.configureExtension(typeOf(TestExtension), new Action<TestExtension>() {
            void execute(TestExtension t) {
                t.call(2)
            }
        })

        then:

        BasePluginExtension baseExtension = project.getExtensions().create(BasePluginExtension.class, "base", DefaultBasePluginExtension.class, project);

        addConvention(project, baseExtension);
        configureExtension(project, baseExtension);
        configureBuildConfigurationRule(project);
        configureArchiveDefaults(project, baseExtension);
        configureConfigurations(project);

    }

    public <T> T configureExtension(String name, Action<? super T> action) {
        ExtensionHolder<T> extensionHolder = uncheckedCast(extensions.get(name));
        if (extensionHolder != null) {
            return extensionHolder.configure(action);
        }
        throw unknownExtensionException(name);
    }

    public <T> void configureExtension(TypeOf<T> type, Action<? super T> action) {