pub fn package(mut self, package: impl AsRef<str>) -> Self {
        self.package = Some(package.as_ref().to_owned());
        self
    }
Set the package this Service is part of.

This value will be used as part of the route for calling this service.
Routes have the form: `/<package_name>.<service_name>/<method_route_name>`
tonic-build/src/manual.rs