pub fn client_attribute<P: AsRef<str>, A: AsRef<str>>(mut self, path: P, attribute: A) -> Self {
        self.client_attributes
            .push_struct(path.as_ref().to_string(), attribute.as_ref().to_string());
        self
    }
Add additional attribute to matched service clients. Matches on the service name.
tonic-build/src/prost.rs