How to use the @alfresco/adf-core.AppConfigService function in @alfresco/adf-core

beforeEach(async(() => {
        service = new TaskFilterService(
            new AlfrescoApiServiceMock(new AppConfigService(null), new StorageService()),
            new LogService(new AppConfigService(null)));
        jasmine.Ajax.install();
    }));

beforeEach(async(() => {
        alfrescoApiMock = new AlfrescoApiServiceMock(new AppConfigService(null), new StorageService());
        identityUserService = TestBed.get(IdentityUserService);
        spyOn(identityUserService, 'getCurrentUserInfo').and.returnValue(cloudMockUser);
        service = new TaskCloudService(alfrescoApiMock,
                                           new AppConfigService(null),
                                           new LogService(new AppConfigService(null)),
                                           identityUserService);

    }));

beforeEach(async(() => {
        alfrescoApiMock = new AlfrescoApiServiceMock(new AppConfigService(null), new StorageService());
        identityUserService = TestBed.get(IdentityUserService);
        spyOn(identityUserService, 'getCurrentUserInfo').and.returnValue(cloudMockUser);
        service = new TaskCloudService(alfrescoApiMock,
                                           new AppConfigService(null),
                                           new LogService(new AppConfigService(null)),
                                           identityUserService);

    }));