pub unsafe extern "C" fn ditto_auth_client_set_validity_listener(
    auth_client: &AuthClient,
    ctx: *mut c_void,
    retain: Option<unsafe extern "C" fn(_: *mut c_void)>,
    release: Option<unsafe extern "C" fn(_: *mut c_void)>,
    validity_update_cb: Option<unsafe extern "C" fn(_: *mut c_void, _: c_int, _: c_int)>
)