Function actix_service::apply_cfg_factory

pub fn apply_cfg_factory<F, C, T, R, S>(
    srv: T, 
    f: F
) -> ApplyConfigServiceFactory<F, C, T, R, S> where
    F: FnMut(C, &mut T::Service) -> R,
    T: ServiceFactory<Config = ()>,
    T::InitError: From<T::Error>,
    R: Future<Output = Result<S, T::InitError>>,
    S: Service, 

Convert Fn(&Config, &mut Service) -> Future<Service> fn to a NewService Service get constructor from NewService.