You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: lib.rs
    path of file: ./repos/firezone/rust/connlib/clients/apple/src
    
    the code of the file until where you have to start completion: // Swift bridge generated code triggers this below
#![allow(clippy::unnecessary_cast, improper_ctypes, non_camel_case_types)]

use connlib_client_shared::{
    file_logger, keypair, Callbacks, Error, LoginUrl, ResourceDescription, Session,
};
use ip_network::IpNetwork;
use secrecy::
    
    fn get_system_default_resolvers(&self) -> Result<Option<Vec<IpAddr>>, Self::Error> {
        let resolvers_json = self.inner.get_system_default_resolvers();
        tracing::debug!(
            "get_system_default_resolvers returned: {:?}",
            resolvers_json
        );

        let resolvers: Vec<IpAddr> = serde_json::from_str(&resolvers_json)
            .expect("developer error: failed to deserialize resolvers");
        Ok(Some(resolvers))
    }