Function actix_service::new_apply_cfg

pub fn new_apply_cfg<F, C, T, R, S>(
    srv: T, 
    f: F
) -> impl NewService<Config = C, Request = S::Request, Response = S::Response, Error = S::Error, Service = S, InitError = T::InitError> + Clone where
    C: Clone,
    F: FnMut(&C, &mut T::Service) -> R,
    T: NewService<Config = ()>,
    R: IntoFuture<Error = T::InitError>,
    R::Item: IntoService<S>,
    S: Service, 

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